Motor pattern generation of the posterior cardiac plate-pyloric system in the stomatogastric ganglion of the mantis shrimp Squilla oratoria

Activity patterns of the constituent neurons of the posterior cardiac plate-pyloric system in the stomatogastric ganglion of the mantis shrimp Squilla oratoria were studied by recording spontaneous burst discharges intracellularly from neuronal somata. These neurons were identified electrophysiologically, and synaptic connections among them were qualitatively analysed. The posterior cardiac plate constrictor, pyloric constrictor, pyloric dilator and ventricular dilator motoneurons, and the pyloric interneuron were involved in the posterior cardiac plate-pyloric system. All the cell types could produce slow burst-forming potentials which led to repetitive spike discharges. These neurons generated sequentially patterned outputs. Most commonly, the posterior cardiac plate neuron activity was followed by the activity of pyloric constrictor neurons, and then by the activity of pyloric dilator/pyloric interneuron, and ventricular dilator neurons. The motoneurons and interneuron in the posterior cardiac plate-pyloric system were connected to each other either by electrical or by inhibitory chemical synapses, and thus constructed the neural circuit characterized by a wiring diagram which was structurally similar to the pyloric circuit of decapods. The circuitry in the stomatogastric ganglion was strongly conserved during evolution between stomatopods and decapods, despite significant changes in the peripheral structure of the foregut. There were more electrical synapses in stomatopods, and more reciprocal inhibitory synapses in decapods.Abbreviations EJP excitatory junctional potential - IPSP inhibitory postsynaptic potential - CoG commissural ganglion - CPG central pattern generator - ion inferior oesophageal nerve - OG oesophageal ganglion - pcp posterior cardiac plate - son superior oesophageal nerve - STG stomatogastric ganglion - stn stomatogastric nerve - PY pyloric constrictor - PD pyloric dilator - VD ventricular dilator - AB pyloric interneuron - lvn lateral ventricular nerves - tcpm transverse cardiac plate muscle     

Ionic composition of endolymph and perilymph in the inner ear of the oyster toadfish, Opsanus tau

The concentrations of free Na+, K+, Ca(+, and Cl(-)in endolymph and perilymph from the inner ear of the oyster toadfish, Opsanus tau, were measured in vivo using double-barreled ion-selective electrodes. Perilymph concentrations were similar to those measured in other species, while endolymph concentrations were similar to those measured previously in elasmobranch fish, though significantly different from concentrations reported in mammals. Perilymph concentrations (mean +/- std. dev.) were as follows: Na+, 129 mmol l(-1) +/- 20; K+, 4.96 mmol l(-1) +/- 2.67; Ca2+, 1.83 mmol l(-1) +/- 0.27; and Cl(-), 171 mmol l(-1) +/- 20. Saccular endolymph concentrations were Na+, 166 mmol l(-1) +/- 22; K+, 51.4 mmol l(-1) +/- 16.7; Ca2+, 2.88 mmol l(-1) +/- 0.27; and Cl(-), 170 mmol l(-1) +/- 12; and semicircular canal (utricular vestibule) endolymph concentrations were Na+, 122 mmol l(-1) +/- 15; K+, 47.7 mmol l(-1) +/- 13.2; Ca2+, 1.78 mmol l(-1) +/- 0.48; Cl(-), 176 mmol l(-1) +/- 27. The relatively high concentrations of Ca2+ and Na+ in the endolymph may have significant implications for the physiological function of the mechanoelectrical transduction channels in the vestibular hair cells of fish compared to those of their mammalian counterparts.     

Physical map of the nrdA-nrdB-ftsB-glpT region of the chromosomal DNA of Escherichia coli

Seven pLC plasmids (pLC 3-46, 8-12, 8-24, 8-29, 14-12, 19-24 and 42-17) which complemented nrdA, nrdB, ftsB and/or glpT mutations of Escherichia coli were analyzed. A restriction map of each plasmid was constructed and restriction fragments were subcloned into pBR322. A physical map of approx. a 15 X 10(6) Mr segment of the chromosomal DNA was deduced from the overlapping region of the pLC plasmids. The pLC plasmids and newly constructed plasmids were examined for the ability to rescue the mutations. The complementation tests defined the location of the genes in the 15 X 10(6) Mr segment in the following order: nrdA-nrdB-ftsB-glpT. Functional nrdAB and ftsB genes were located in the 3.1 X 10(6) Mr EcoRI-PstI fragment.     

Development of the hypothalamic-pituitary-axis in the ovine fetus: ontogeny of action of ovine corticotropin-releasing factor

In samples from twenty chronically cannulated ovine fetuses the plasma immunoreactive adrenocorticotrophin (ACTH) concentrations were 12.5 +/- 3.2(8), 15.2 +/- 4.1(9) and 21.2 +/- 5.6(8) pg/ml at periods, prior to parturition, of -30 to -35, -25 to -29 and -20 to -24 days respectively. Values are mean +/- SEM (number of samples). These values were not significantly different from each other but were significantly lower (P less than 0.02) than values in the next two age groups -36.0 +/- 4.9(7) pg/ml at -19 to -15 days, and 39.6 +/- 6.6(11) pg/ml at -14 to -9 days. A further significant increase (P less than 0.05) occurred in the -8 to -3 day period, ACTH being 53.9 +/- 5.4(12) pg/ml. On day of delivery two samples had values of 325 and 360 pg/ml. A single injection, intravenously of 1.0 microgram ovine corticotrophin-releasing factor (O-CRF), caused a significant increase in fetal plasma ACTH concentrations in fetuses of -6 to -23 days prior to delivery but not in fetuses -24 to -35 days prior to parturition. The maximum values of ACTH after O-CRF were significantly greater in fetuses -2 to 0 days prior to parturition than in younger fetuses (P less than 0.01). In 6 experiments in 4 fetuses (parturition -1 to -13 days) the effect of 1.0 microgram O-CRF persisted for at least 2.5 h. The results support the hypothesis that the pituitary release of ACTH changes sensitivity to hypothalamic O-CRF at least twice during the last fifth of gestation; an increasing sensitivity is seen as term approaches.     

Influences of IGF-I gene disruption on the cellular profile of the diaphragm

The impact of a targeted disruption of the Igf1 gene, encoding the insulin-like growth factor I (IGF-I), on diaphragm (DIA) cellularity was studied in 2-mo-old homozygous mutant [IGF-I(-/-)] mice and their wild-type [WT; i.e., IGF-I(+/+)] littermates. DIA fiber types were classified histochemically. DIA fiber cross-sectional areas (CSA) were determined from digitized muscle sections, and fiber succinate dehydrogenase (SDH) activity was determined histochemically using a microdensitometric procedure. An acidic ATPase reaction was used to visualize capillaries. Myosin heavy chain (MyHC) isoforms were identified by SDS-PAGE, and their proportions were determined by scanning densitometry. The body weight of IGF-I(-/-) animals was 32% that of WT littermates. DIA fiber type proportions were unchanged between the groups. The CSAs of types I, IIa, and IIx DIA fibers of IGF-I(-/-) mutants were 63, 68, and 65%, respectively, those of WT animals (P < 0.001). The DIA thickness and the number of fibers spanning its entire thickness were reduced by 36 and 25%, respectively, in IGF-I(-/-) mice (P < 0. 001). SDH activity was significantly increased in all three types of DIA fibers of IGF-I(-/-) mutants (P < 0.05). The number of capillaries per fiber was reduced approximately 30% in IGF-I(-/-) animals, whereas the capillary density was preserved. The proportions of MyHC isoforms were similar between the groups. Muscle hypoplasia likely reflects the importance of IGF-I on cell proliferation, differentiation, and apoptosis (alone or in combination) during development, although reduced cell size highlights the importance of IGF-I on rate and/or maintenance of DIA fiber growth in the postnatal state. Reduced capillarity may result from both direct and indirect influences on angiogenesis. Improved oxidative capacity likely reflects DIA compensatory mechanisms in IGF-I(-/-) mutants.     

The carboxyl-terminal region of the geranylgeranyl diphosphate synthase is indispensable for the stabilization of the region involved in substrate binding and catalysis

Rat geranylgeranyl diphosphate synthase (GGPS) and its deletion mutants from the carboxyl terminus were analysed using Escherichia coli harbouring pACYC-crtIB, which contains crtI and crtB encoding the carotenoid biosynthetic enzymes. Mutants (delta-4, -8, -12 and -16) produced lycopene-derived red colour, but mutants (delta-17, -18, -19, -20, -23, -57 and -70) did not. The histidine-tagged mutants (delta-4, -8, -12 and -16) were overexpressed in E. coli BL21 (DE3) and purified in a stable form by nickel affinity chromatography except for one mutant (delta-16). The farnesyl-transferring activities of wild-type GGPS, delta-4, -8 and -12 mutants were relatively in a ratio of 1.0, 0.84, 0.26 and 0.0015. Each Km value of the four recombinants were estimated to be 0.71, 2.0 2.8 and 55 microM for farnesyl diphosphate and to be 2.9, 5.1, 56 and >100 microM for isopentenyl diphosphate, respectively. Allylic substrate specificities of these recombinants were estimated by quantitative analysis of the products, revealing that delta-8 and -12 mutants lack the ability to accept dimethylallyl and geranyl diphosphates compared to wild-type GGPS and delta-4 mutant. These results suggest that the KMFTEENE residing on the carboxyl-terminal sequence of GGPS stabilizes the active region involved in the substrate binding and catalysis.     

Toward the elucidation of the catalytic mechanism of the mono-ADP-ribosyltransferase activity of Pseudomonas aeruginosa exotoxin A

The catalytic mechanism for the mono-ADP-ribosyltransferase activity of Pseudomonas aeruginosa exotoxin A was investigated by steady-state and stopped-flow kinetic analyses. The rate constants for binding of the NAD(+) substrate to the enzyme were found to be 4.7 +/- 0.4 microM(-1) s(-1) and 194 +/- 15 s(-1) for k(on) and k(off), respectively. The k(on) and k(off) rate constants for the eEF-2 substrate binding to the enzyme were 320 +/- 39 microM(-1) s(-1) and 131 +/- 22 s(-1), respectively. A potent, competitive inhibitor against the enzyme, 1,8-naphthalimide, bound the enzyme with k(on) and k(off) rates of 82 +/- 9 microM(-1) s(-1) and 51 +/- 6 s(-1), respectively. Furthermore, the binding on and off rates for the reaction products, ADP-ribose and nicotinamide, were too rapid for detection with the stopped-flow technique. Investigation of the pre-steady-state kinetics for the ADP-ribose transferase activity of the toxin-enzyme showed that there is no pre-steady-state complex formed during the catalytic cycle. Binding of NAD+ and smaller compounds representing the various parts of this substrate were investigated by the fluorescence quenching of the intrinsic toxin fluorescence. The binding data revealed a significant structural change in the enzyme upon NAD+ binding that could not be accounted for on the basis of the sum of the structural changes induced by the various NAD+ constituents. Product inhibition studies were conducted with nicotinamide and eEF-2-ADP-ribose, and the results indicate that the reaction involves a random-order ternary complex mechanism. Detailed kinetic analysis revealed that the eEF-2 substrate shows sigmoidal kinetic behavior with the enzyme, and fluorescence resonance energy transfer measurements indicated that wheat germ eEF-2 is oligomeric in solution.     

Putative osmolytes in the kidney of the Australian brush-tailed possum,Trichosurus vulpecula

The Australian brush-tailed possum, Trichosurus vulpecula, is capable of producing a moderately concentrated urine, at least up to 1300 mOsm l(-1). Kidneys of adult animals fed in captivity on a normal diet with ready access to water were analysed. The inner medullary regions were found to have moderately high concentrations of sodium (outer medulla, 367+/-37; inner medulla 975+/-93 mmol kg(-1) dry wt.), chloride (outer medulla 240+/-21; inner medulla 701+/-23 mmol kg(-1) dry wt.) and urea (outer medulla, 252+/-62; inner medulla, 714+/-69 mmol kg(-1) protein). When the animals were fed on a 'wet diet', amounts of these substances in the outer medulla and cortex were reduced, although with the exception of urea these changes were not significant. There were highly significant changes in amounts of Na(+), Cl(-) and urea in the inner medulla (Na(+), 566+/-7; Cl(-), 422+/-9 mmol kg(-1) dry wt.; urea 393+/-84 mmol kg(-1) protein). Likewise, the inner medulla of animals fed a 'dry diet' with limited access to water showed highly significant increases in the same substances (Na(+), 1213+/-167; Cl(-), 974+/-137 mmol kg(-1) dry wt.; urea, 1672+/-98 mmol kg(-1) protein). Inositol was found in the outer medulla (224+/-90 mmol kg(-1) protein) and inner medulla (282 mmol kg(-1) protein) as was sorbitol (outer medulla, 62+/-20; inner medulla, 274+/-72 mmol kg(-1) protein). Both these polyols were reduced in amount in renal tissue from 'wet diet' animals, and increased in 'dry diet' animals, but the changes were not statistically significant. The methylamines, betaine and glycerophosphorylcholine (GPC), showed a similar pattern, but both were significantly elevated in the inner medulla of 'dry diet' animals (betaine 154+/-57 to 315+/-29 mmol kg(-1) protein; GPC 35+/-7 to 47+/-10 mmol kg(-1) protein). It was concluded that in this marsupial the concentrating mechanism probably functions in a similar way to that in higher mammals, and that the mechanism of osmoprotection of the medulla of the kidney involves the same osmolytes. However, the high ratio of betaine to GPC in the inner medulla resembles the situation in the avian kidney.     

Differential Changes in the Content of Amino Acid Neurotransmitters in Discrete Regions of the Rat Brain Prior to the Onset and During the Course of Homocysteine-Induced Seizures

Changes in amino acid concentrations were investigated in selected regions of rat brain prior to the onset and during the course of epileptiform seizures induced by L-homocysteine. The concentration of gamma-aminobutyric acid (GABA) decreased preictally in substantia nigra (-18%), caudate putamen (-26%), and inferior colliculus (-46%). After seizure onset, the GABA content was further reduced in substantia nigra (-31%) and additionally in hippocampus (-18%). Preictal taurine levels were elevated in globus pallidus (+26%) and caudate putamen (+13%) but returned to normal after seizure onset. However, in hippocampus, taurine decreased both preictally (-22%) and after seizure onset (-56%). Glycine was reduced preictally only in globus pallidus (-13%). After seizure onset the direction of its concentration change varied in the brain regions studied. Glutamate levels decreased preictally in hippocampus (-10%) and hypothalamus (-46%) but increased in globus pallidus (+14%). Normal levels were detectable after seizure onset in hypothalamus and globus pallidus but a further reduction in hippocampus (-59%) and significant reductions in substantia nigra (-15%) and caudate putamen (-17%) were detected. Aspartate was elevated in hippocampus, both preictally (+49%) and after seizure onset (+21%) while at the same phases in globus pallidus a consistent reduction (-30%) was observed. The glutamine content increased preictally in globus pallidus (+41%) and hypothalamus (+36%), and in all brain areas during the ictal phase of seizure, the hippocampus exhibiting a dramatic increase (approximately 300%). The contents of serine and alanine were altered in most regions studied only after seizure onset, with the exception of the hippocampus, where a decrease (-41%) of serine was observed preictally.     

Pharmacokinetics of the enantiomers of verapamil in the dog

The intravenous (0.5 mg/kg) and oral (5 mg/kg) dose kinetics of verapamil were studied in 6 dogs during steady-state oral verapamil dosing (5 mg/kg every 8 h for 3 days). Racemic verapamil and norverapamil, a metabolite of verapamil, were quantitated in plasma by HPLC-fluorescence detection. The verapamil peaks eluting off the column were collected and rechromatographed on an Ultron-OVM column, which resolved the two verapamil enantiomers. After intravenous administration, the systemic clearance and apparent volume of distribution of (?)-(S)-verapamil were nearly twice that of the (+)-(R)-isomer. There was no difference in the elimination half-lives between the two isomers. After oral administration, the oral clearance of (?)-(S)-verapamil was 20 times that of the (+)-(R)-isomer. The apparent bioavailability of (+)-(R)-verapamil was over 14 times that of (?)-(S)-verapamil. The plasma protein binding of the (+)-(R)-isomer was slightly higher by 5% than (?)-(S)-verapamil; however, this effect was not enough to account for the difference between the apparent volume of distribution of the enantiomers, indicating that the tissue binding of (?)-(S)-verapamil was greater than that of the (+)-(R)-isomer. This data on the disposition of the enantiomers of verapamil in the dog is similar to that reported for man and demonstrates that the dog may be an appropriate animal model for man in future studies on the disposition of the enantiomers of verapamil. © 1993 Wiley-Liss, Inc.     

Synthesis and immunogenic properties of peptides--fragments of the immunodominant regions of the VP1 protein of the Asia-1 type of foot- and-mouth disease virus

Potential immunodominant epitopes were predicted on the basis of a theoretical analysis of the antigenic structure of the VP1 protein of the type Asia-1 foot-and-mouth disease virus. Peptides corresponding to the 140-153, 136-153, 132-153, 143-157, 137-157, and 193-208 fragments of the VP1 protein sequence were synthesized by the solid phase method, and the immunogenic properties of the peptides were studied on guinea pigs. The shortest peptide exhibiting the protective effect was found to correspond to the, 140-153 fragment of the VP1 sequence. The Plm-(Gly)3-(140-153)-(Gly)2-Lys(Plm)-Leu and [Ac-(140-153)-(Gly)3]8-(Lys)7-Gly synthetic constructions in combination with adjuvants provided up to 80% protection of immunized animals against infection with the foot-and-mouth disease virus.     

Coding of vibration by neurones of the dorsal column nuclei in the pigeon

Whereas the function of mechanoreceptors is well known in birds there are no detailed investigations of central processing. Therefore the characteristics of neurones in a first relay, the dorsal column nuclei (nuclei gracilis et cuneatus and the nucleus cuneatus externus), were studied electrophysiologically by recording responses from individual neurones to mechanical stimulation of skin and deep tissue.Of 140 units 84 were cutaneous neurones. The remainder were tap- and deep-neurones. Tap-neurones were activated by sharp brief taps. Activity in deep-neurones was comparable to joint and tendon receptors but not to muscle spindles. Thirty-four cutaneous neurones were vibration sensitive neurones, 36 were slowly adapting neurones and 14 neurones were rapidly adapting and fast habituating cells. Vibration sensitive neurones were most sensitive to 200 to 500 Hz. Frequencies above 100 Hz elicited phase coupled responses.Within the nn. gracilis et cuneatus 61 were cutaneous neurones, 13 were deep-neurones and 7 were tap-cells. Within n. cuneatus externus 17 were cutaneous units, 21 were deep-neurones and 11 were tap-neurones. No vibration sensitive neurones were found within n. cuneatus externus. This means that coding for vibration is represented in the nn. gracilis et cuneatus.Abbreviations CE n. cuneatus externus - DCN dorsal column nuclei - GC n. gracilis et cuneatus - HC Herbst corpuscle - PH phasic and habituating - Imps./s Impulses per second - INTH interval histogram - PSTH peristimulus time histogram - PHASE Phase histogram - RF receptive field - SA slowly adapting - Vec. vector strength     

Multiplication of the dictyosome during the formation of autospores in the green alga Chlorococcum infusionum

Numerical changes in dictyosomes during the formation of autospores in a green alga, Chlorococcum infusionum, were investigated by electron microscopy. Two dictyosomes were seen near the nucleus in young vegetative cells. Four dictyosomes were seen in large mononucleate cells which appeared to enter mitosis soon. Binucleate cells contained 4 or 8 dictyosomes, the latter number being found in the large binucleate cells. Large tetranucleate cells contained 16-25 dictyosomes in each cell. Dictyosomes consisted of about 4 cisternae with a diameter of 0.4-0.6 micron in mono- to tetranucleate cells. Cytokinesis began with the formation of the septa during the third nuclear division, and 16 cells were finally formed. Dictyosomes did not increase in number in 8- and 16-nucleate cells. In septum-forming cells, dictyosomes were 0.6-1.0 microns in diameter, with 6-9 cisternae. A single dictyosome was included in each of the 16 resultant cells. These observations suggest that the dictyosomes multiply in association with the multiplication of the nuclei without correlation with formation of the cell wall or cytokinesis.     

The effects of hypoosmotic infusion on the composition of renal tissue of the Australian brush-tailed possum Trichosurus vulpecula

Although the occurrence of organic osmolytes in the inner medulla of the marsupial kidney has been recently reported [Comp. Biochem. Physiol. (2002) 132B 635-644], changes in these substances, in response to water loading in vivo, has not been studied. Adult Trichosurus vulpecula, the Australian brush-tailed possum, were subjected to water deprivation for 48 h. Following anaesthesia and unilateral nephrectomy, the animals were perfused with hypo-osmotic saline (80 mmol l(-1); 1.5 ml min(-1)) for 60 min. This resulted in a rapid increase in urine volume and a corresponding fall in urine osmolality. At the end of the infusion the animals were killed and the second kidney removed. Analysis of the renal tissue revealed that water content of cortical, outer and inner medullary regions of the kidney increased slightly following infusion, while sodium, and chloride contents of all three regions fell. Potassium contents, on the other hand, were barely changed. Of the organic osmolytes determined, very significant decreases in the inner medulla, following infusion, were found for sorbitol (from 397+/-79 to 266+/-49 mmol kg(-1) protein), inositol (247+/-23 to 190+/-25 mmol kg(-1) protein), and betaine (464+/-70 to 356+/-21 mmol kg(-1) protein), while only inositol was significantly decreased in the outer medulla (197+/-22 to 150+/-16 mmol kg(-1) protein). Glycerophosphorylcholine levels were low throughout the kidney and were not significantly affected by the infusion. It was concluded that inositol and sorbitol play a significant role as compatible organic osmolytes in the possum kidney, while betaine functions as the principal counteracting osmolyte. Amino acid levels in the cortex and outer medulla showed no overall change in amount following infusion, although there were highly significant changes in individual amino acids. In the inner medulla there was a highly significant reduction in total amino acids with infusion, largely due to a fall in amounts of taurine (104+/-4 to 75+/-17 mmol kg(-1) protein), and glycine (97+/-15 to 71+/-18 mmol kg(-1) protein). A fall in free amino acid levels in the inner medulla appears to significantly contribute to the process of intracellular osmotic adjustment during an induced diuresis.     

The tight junction proteins expression in the epithelium of the small intestines in a rat

Proteins' expression of tight junction proteins in rat small intestine was analyzed by means of immunohistochemistry and Western blotting. Claudins -1, -2, -3, -4, -5, -7 and occludin were analyzed. Confocal laser-scanning microscopy revealed differences in the subcellular distributions of these proteins. Claudins-1, -2, -3, -4, -5, and -7 were localized within the tight junction complex and were also detectable in subjunctional regions. Distributed subcellular localization of these proteins may reflect their different roles during formation of epithelial cell layers as well as in paracellular transport of ions in the small intestine.     

Synthesis of polypeptides by the cervix of the baboon (Papio anubis)

Administration of oestradiol to ovariectomized baboons caused the epithelium of the cervix to differentiate into tall columnar cells that were ciliated or secretory. Administration of progesterone in the presence or absence of oestradiol altered the appearance of the lining epithelium, suggesting a decrease in secretory activity. Fluorographs of media from cultures of tissue from steroid-treated animals reflected changes in polypeptide biosynthesis which correlated with the morphological observations: 6 polypeptides (Mr 88,000-37,000; pI 5.5-6.0) were observed in all treatment groups and, except for relative changes in intensity, these polypeptides were electrophoretically similar to those synthesized by the endometrium. A new group of low molecular weight polypeptides (Mr 23,000-20,000, pI greater than 8.0-5.5) and a basic protein (Mr 160,000) were synthesized and released in the oestradiol-dominated animal. These polypeptides were distinct to the cervical mucosa since they were not observed in the endometrium or oviduct. Progesterone suppressed the synthesis of the low molecular weight acidic polypeptides (Mr 23,000-20,000; pI 6.1-5.5) but maintained the synthesis of the basic polypeptides (Mr 23,000-20,000; pI greater than 8). Treatment with progesterone +/- oestradiol did not appear to induce the synthesis of any new major polypeptides in the cervical epithelium. These results suggest that oestradiol induces the synthesis of a group of cervix-specific polypeptides and progesterone antagonizes the action of oestradiol in the baboon cervix.     

Effect of sulfhydryl compounds on the automatism of the pacemakers]

Experiments were performed on the isolated rabbit hearts and also on the hearts with complete atrioventricular block; a study was made of the effect of an excess or deficiency of the sulfhydryl groups on the automatism of the cardiac pace makers. Unithiol and cysteine in concentrations of 1-10(-6)-1-10(-4) g/ml were used as donors of sulfhydryl groups; deficiency of these groups was induced by the alloxan administration in concentrations of 1-10(-5)-5-10(-5) g/ml. Changes in the sulfhydryl group content produced no marked effect on the automatism of the synoatrial node. An excess of sulfhydryl groups promoted poststimulation depression of the automatism of the potential pace makers of the cardiac ventricles and could lead to the origination of Luciani's periods. On the contrary, in case of a deficiency of the sulfhydryl groups there was a sharp elevation of the automatism of the ventricular pace makers, the atrioventricular conduction became disturbed, and the poststimulation depression of the automatism became considerably diminished. Disturbances of the cardiac activity caused by the sulfhydryl group deficiency were completely eliminated by unithiol or cysteine.     

A study of 3891 cases of mycoses in the tropics.

4103 cases suspected of mycoses were analysed as to sex, age and site of disease and 3891 were proved cases. This group formed 50% of total mycoses or 13-93% of all dermatoses recorded in the Government General Hospital, Madras, during the period of study. There were 66-26% adult female, 27-6% adult male and 6-14% were below 13 years. Dermatophytoses were found in 73-5%; the other common diseases were tinea versicolor (17-68%) and candidiasis (12-43%). Multiple sites of involvement or more than 1 disease in the same individual were mostly observed. The incidence of piedra (0-1%) and deep mycoses (0-156%) was very low. Mycetoma was the common disease (5/6) in deep mycoses. In dermatophytoses, tinea corporis (49-71%) and tinea cruris (47-85%) commonest; tinea axillaris (3-42%), tinea capitis (1-72%) and tinea barbae (1-29%) were less common. The incidence of tinea manuum, tinea pedis and tinea unguium was similar (4-97%-6-38%). High temperature and humidity were related to the higher incidence of tinea corporis, tinea cruris and tinea versicolor. Mainly children suffered from tinea capitis. All other mycoses were commonly found in adults between 2nd and 3rd decades. In all mycoses but candidiasis, female predominated. Cutaneous candidiasis was mainly a problem of housewives. Among the dermatophytes Trichophyton violaceum was predominant (33-7%) followed by T. rubrum (32-6%). Trichophyton schoenleinii and M. gypseum were rarely isolated. From mycetoma, Madurella mycetomii, Nocardia braziliensis, N. asteroides and Actinomadura spp. were isolated. Demonstration of Cryptococcus laurentii in 1 case is reported in this area for the first time.     

Development of the stable isotope tracer approach for studies of copper turnover in the rat and mouse

The stable isotope tracer approach was explored for long-term investigations of copper turnover in the adult rat and mouse, with inductively coupled plasma mass spectrometry for isotope measurements. The isotopic measurement method permitted precision and accuracy of <1.0%, with an overall sample blank of <0.05 microg copper. Rats were fed a copper-deficient diet and deionized water with (+Cu) or without (-Cu) copper (20 microg/ml). Both groups underwent a single-day replacement of drinking water with 20 microg/ml of (65)Cu. Compared with the baseline isotope ratio ((65)Cu/(63)Cu) of 0.462 +/- 0.002, blood plasma ratios for the +Cu group on days 2, 7, and 14 postdosing were 0.702 +/- 0.021, 0.557 +/- 0.004, and 0.474 +/- 0.001, respectively. The corresponding data for liver were 1.652 +/- 0.018, 0.560 +/- 0.005, and 0.482 +/- 0.001, respectively. For the -Cu group, respective plasma ratios were 1.580 +/- 0.04. 0.917 +/- 0.02, and 0.664 +/- 0.01 for days 2, 7, and 14 postdosing, and the ratios for liver were 0.987 +/- 0.02, 0.876 +/- 0.04, and 0.739 +/- 0.03. Mice previously made copper deficient to varying degrees were given a single-day replacement with the label. When the 24-hour postdosing isotope ratios in the livers of these mice were correlated with the activity of plasma ceruloplasmin, a negative correlation (r = -0.85) was observed. Isotope enrichment in both rats and mice was greater in the copper-deficient animals compared with the controls.     

Etiology of purulent septic diseases and the antibiotic resistance of the isolated causative agents

Among the causative agents of purulent septic diseases in the surgical hospital, 25 microbial species were isolated; of these, the prevailing species were Staphylococcus aureus (19.86 +/- 1.07%), Escherichia coli (16.5 +/- 0.99%) and Pseudomonas aeruginosa (10.06 +/- 0.8%). From environmental objects in the hospital 14 microbial species were isolated, among them bacteria of the genus Enterobacter (27 +/- 1.7%), E. coli (19.07 +/- 1.48%), S. aureus (14.7 +/- 1.31%), Klebsiella pneumoniae (13.73 +/- 1.31%), P. aeruginosa (7.33 +/- 0.98%). During 3 years of observation the isolation rate of K. pneumoniae from different environmental objects was found to increase threefold to 24.7 +/- 2.7%. The results of the study of the microbial picture in surgical hospitals, as well as the antibiotic resistance of circulating causative agents, should be borne in mind while taking epidemic control measures.