Distribution of diaphragmatic lymphatic stomata

In seven anesthetized rabbits we measured the size, shape, and density of lymphatic stomata on the peritoneal and pleural sides of the diaphragm. The diaphragm was fixed in situ and processed for scanning electron microscopy. Results are from 2,902 peritoneal and 3,086 pleural fields (each 1,620 microns 2) randomly chosen from the various specimens. Stomata were seen in 9% of the fields examined, and in 30% of the cases they appeared grouped in clusters with 2-14 stomata/field. Stoma density was 250 +/- 242 and 72 +/- 57 (SD) stomata/mm2 on peritoneal and pleural sides, respectively, and it was similar over the muscular and tendinous portion of the two surfaces. The maximum diameter ranged from less than 1 to approximately 30 microns, with an average value of 1.2 +/- 3.1 micron. The ratio of the maximum to the minimum diameter and the surface area averaged 2 +/- 1.4 and 0.7 +/- 2.4 micron 2, respectively. The maximum and minimum diameter and surface area values followed a lognormal frequency distribution, suggesting that stomata geometry is affected by diaphragmatic tension.     

Genetic structure of the population of Sicily.

Genetic heterogeneity within Sicily was investigated on the basis of ACP1, ADA, ESD, GLO1, PGD, PGM1, PGM2, SODA, ABO, and MN gene frequencies, and compared to those of other regions of Italy for which these same loci have been examined. Correspondence analysis revealed no differences within the island, at least at the provincial level, but showed genetic differentiation among Italian regions, distinctly clustering northern, central, and southern populations, respectively. These data indicate a close relationship between Sicily and southern Italy. In addition, the contribution of Middle Eastern populations to the gene pool of Sicily was evident.     

Nuclear matrix involvement in sperm head structural organization

Summary— In the sperm nuclei the DNA is packaged into a highly condensed form and is not organized into nucleosome and solenoid but is bound and stabilized mainly by the protamines that arrange the DNA in an almost crystalline state. As demonstrated for somatic cells, the sperm DNA has been reported to be organized in loop domains attached to the nuclear matrix structures. However, the possible role of the sperm head matrix in maintaining the loop organization in absence of a typical nucleosomal structures has not been fully elucidated. By using in situ nick translation at confocal and electron microscope level, we analyzed the organization of the DNAprotamine complex and its association with the sperm nuclear matrix. The data obtained indicate that the chromatin organization in sperm nuclei is maintained during the sperm condensation by means of interactions with the nuclear matrix at fixed sites. The fine stucture of sperm nucleus and of sperm nuclear matrix, investigated on sections and replicas of freeze-fractured specimens, suggests that the lamellar array, observed by freeze-fracturing in the sperm nuclei, could depend on the inner matrix which presents a regular organization of globular structures possibly involved in the maintenance of chromatin domains in highly condensed sperm nuclei also.     

Permineralized seed fern cupules from the Triassic of Antarctica: implications for cupule and carpel evolution

In this paper we describe the first anatomically preserved Mesozoic seed fern cupule–Petriellaea. The multiovulate cupules were produced singly at the end of a short dichotomizing axis. Cupules are bilateral with a dorsal groove and transverse narrow ventral opening. The vascular system of the cupule consists of a series of traces that extend up the dorsal surface of the cupule and down the ventral face. Ovules are orthotropus, sessile, and borne on the adaxial surface of the leaflike cupule either singly or in multiple rows. They are up to 1.5 mm long, triangular in transverse section, and characterized by a multilayered integument. Nucellus and integument are fused throughout their length, but no pollen chamber is present. In the chalaza is a small vascular disc of transfusion tracheids that represents the extent of the ovule vascular system. Ovules are interpreted as being fossilized at a prepollination stage, although a few possess some evidence of a cellularized megagametophyte. These permineralized cupules indicate that in at least one Mesozoic seed fern group, ovule enclosure resulted from the transverse folding (tip to petiole) of a megasporophyll bearing adaxial ovules. Cupule morphology and ovule enclosure in other Late Paleozoic and Mesozoic seed ferns is discussed.     

Simulation of a reactor for glucose isomerization to fructose by immobilized glucose isomerase with continuous enzyme renewal

Two different dispositions of laboratory-scaled columns have been tested to simulate the isomerization of glucose to fructose in a mobile bed reactor where exhausted immobilized glucose isomerase is continuously renewed. If the simulation columns working at 65°C are arranged in parallel and connected to a section for final enzyme exploitation at 75°C, a syrup with constant composition can be produced, at relatively constant total throughput, by feeding the individual columns at flow rate decreasing according to the enzyme decay profile and following a programmed disphased mode of operation.This revised version was published online in October 2005 with corrections to the Cover Date.     

Reduction of vanadate to vanadyl by a strain of Saccharomyces cerevisiae

Three strains of Saccharomyces cerevisiae, SC-1, DBVPG 6173 and DBVPG 6037, were studied for vanadate resistance in complex Sabouraud medium since they did not thrive in different minimal media (yeast nitrogen base with and without amino acids). The strain SC-1 was resistant up to 16 mm of vanadate, whereas the strains DBVPG 6173 and DBVPG 6037 were inhibited by 8 mm and 4 mm vanadate, respectively. The vanadate resistance in strain SC-1 was constitutive and due to the reduction of this oxyanion to vanadyl, which was detected by EPR spectroscopy and visible spectroscopy. The transformation of vanadate to vanadyl took place during the exponential growth phase; 10 mm of vanadate was reduced to vanadyl outside the cells since the oxyanion was not detected in the cell biomass and only a negligible concentration of vanadyl (25 nmoles mg cells dry weight) was found in the biomass. The other two vanadate-sensitive yeast strains only accumulated vanadate and did not reduce the oxyanion to vanadyl.     

Development of a sensitive semi-automatized enzyme immunoassay of leukotriene using acetylcholinesterase-leukotriene C4 as tracer

The obtention of icosanoids tracers of high specific radioactivity (e.g. radioiodinated tracers) has been a prerequisite for the development of radioimmunoassays that would allow the detection of femtomoles amount of these substances from biological medium. However, recent attempts to develope immunoassays using haptens (e.g. prostaglandins or thromboxane B2) labeled with enzymes have turned out to be disappointing because of their poor sensitivity. Using the acetylcholinesterase (AChE) from “electrophorus electricus” as a tracer we have labeled LTC4 after coupling it to the enzyme with 1,5-difluoro-2,4-dinitrobenzene as a bifunctional reagent. The use of 96-well microtiter plates coated with pig anti-rabbit immunoglobulin antibodies (purified by affinity chromatography) has allowed to develop a semiautomatized enzyme immunoassay (EIA). A dispenser was used to add all common reagents (antibody, tracer, enzyme substrate); a washer was used to eliminate the unreacted molecules from the immuno-reactions. After addition of the enzyme substrate (Ellman's reagent), the reaction was allowed to proceed during one hour and the optical density was measured at 414 nm using an automatic reader. Using the same antiserum (kind gift of Dr. Rokach, Merck Frosst, Canada) at appropriate dilutions (1/30,000 for LTC4 AChE versus 1/6,000 for 3HLTC4) the sensitivities were compared. LTC4 was detectable in the range of 3.3 to 84 femtomoles/well corresponding to a 12–75% displacement of initial binding (i.e. approximately 2–50 pg/well) with LTC4-AChE as compared with 80–1000 pg/tube for 3H. The 50% inhibition was approximately obtained at 15 pg/tube, respectively. The determination of LTC4 on human neutrophils stimulated by various stimuli was performed without any extraction. The results obtained by this technique have been validated by comparing them to those obtained using a quantitative HPLC method. It was also possible to use the same labeling technique for prostaglandin D2-methoxamine, 6-keto PGFlα and TXB2. For all these EIA, the 50% diplacement of initial binding was 2–3 pg/well.     

Circannual rhythm of insulin release and hypoglycemic effect of tolbutamide stimulus in healthy man

Four healthy non obese young volunteers were observed for a 24-hr period, every other month, over the course of one year. Tolbutamide was injected i.v. each day of the experiment every four hours. Tolbutamide-induced insulin secretion (T.I.I.S.) was evaluated by planimetrically measuring insulin areas above basal levels. Tolbutamide-induced hypoglycemic effect was evaluated by measuring the blood glucose difference between the 5th and 25th minute after the drug injection (delta G5'-25'). The macroscopic evaluation of T.I.I.S. and delta G5'-25' (mean chronograms) permitted the detection of the existence of a circannual variation of both variables. In particular the maximum level of the blood glucose drop (delta G5'-25') was registered in February. Subsequently the quantification of the rhythm of T.I.I.S. was obtained by fitting a sine curve, according to the Cosinor method. The highest insulin release was confirmed in winter. As previously documented, the existence of a statistically significant circadian rhythm of T.I.I.S. was confirmed in the morning, i.e. the same period of the day in which insulin-induced hypoglycemia occurs.     

The effect of S-adenosyl-L-methionine (SAM) on membrane permeability in the perfused rat liver

S-adenosilmethionine is present in most human tissues and is an important factor for transmethylation, transulphuration and aminopropylation reactions. The compound improves the biological, morphological and histochemical aspects of rat liver following CCl4 intossication. At the same time has been successfully used during chronic liver disease in man. With the aim to better clarify the action mechanism of SAMe some aspects concerning its effects on cell permeability in rat liver, by using the perfusion technique, have been investigated. In particular the capacity of this compound to prevent the enzymatic loss (GPT and GOT) during liver perfusion has been studied. 30 perfusions without SAMe, as control, and 6 by infusing 2 mg of compound during the perfusion time have been accomplished. Varing the perfusion time from 0 to 120 min it has been observed that at any time the presence of the SAMe reduced by about 50% the loss of GOT. Similarly the activity of GPT ranging from 2 to 6 mU/ml indicate that no appreciable enzyme output occurs in presence of SAMe.