Effects of lung congestion and oleic acid injury on the Hering-Breuer reflex

Breathing and the Hering-Breuer (HB) reflex may be stimulated by congestion and by acute lung injury, but there is disagreement about the effects of both stimuli. This study evaluated these effects using greater stimulus isolation and control of secondary interactions than have previously been employed. Pressurization of lung vessels and left heart and oleic acid injury were individually imposed on anesthetized open-chest dogs perfused with an external pump and gas exchanger. Lungs were inflated in steps before and during those stimuli. The HB reflex was evaluated from graphs of breathing frequency (fr) vs. airway pressure. Congestion itself had no significant sustained effect on fr, but it slightly depressed the HB reflex. Oleic acid tachypnea that was depressed to pretreatment fr by inflation, implying enhancement of the HB response. Capsaicin and oleic acid had similar effects. Vagal cooling to 8 degrees C slightly depressed the effects of oleic acid and capsaicin, had no effect on the sustained fr response to congestion, and reversed the inhibitory effect of inflation. A stimulation of breathing or an enhancement of the HB reflex by congestion was not confirmed, but oleic acid increased fr and the HB reflex.     

High-frequency spontaneous deletion of DNA sequences flanked by direct DNA repeats which also contain an internal palindrome

The DNA sequences associated with a very high-frequency, spontaneous deletion event have been determined to be two 11-base direct repeats which also contain an internal 6-base palindrome. A parental M13 replicative form (RF) DNA harboring DNA fragments of the T4 denV gene contained these direct repeats and could only be maintained at 5% of the total RF DNA within an infected cell. The remaining RF DNA was deleted for all intervening sequences between the direct repeats (2.2-kb), but one copy of the direct repeat was retained after the deletion had occurred. This site-specific deletion was highly reproducible in that if parental-sized M13 RF DNA was gel purified and transformed back into cells, the deletion occurred at precisely the same sequence as before. Electron microscopic analyses of DNA extracted from cells transformed with parental-sized DNA revealed the presence of excised 2.2-kb double-stranded circular DNA molecules. This observation thus rules out a copy choice replication/deletion mechanism to account for this high-frequency deletion event.     

Effects of male partners upon proceptivity in ovariectomized estradiol-treated marmosets (Callithrix jacchus)

Effects of male partners upon the expression of female proceptivity were examined in two experiments using 16 ovariectomized marmosets. Experiment 1 showed that the female's proceptive tongue-flicking display (PTF) is triggered specifically by eye contact with the male. Stimulation of PTF by administration of estradiol-17 beta (E2) to ovariectomized females depends in part upon the male's responsiveness to female displays, such as "staring" and "freezing," which may serve to attract his attention and to establish eye contact. Experiment 2 provided evidence that females' proceptivity decreases if their male partners are lesioned in the preoptic area/anterior hypothalamus. Such males are sexually hypoactive and less responsive to the females' visual displays. However, E2 still activates PTF if females succeed in initiating eye contact with males. Results indicate that variability in effects of E2 upon proceptivity in marmosets may be influenced by subtle aspects of facial communication between the sexes as well as by individual differences in hormonal sensitivity. Copulatory activity in males is not essential for E2 to exert its stimulatory action upon proceptivity in female marmosets.     

A single base mutation in the gene for type III collagen (COL3A1) converts glycine 847 to glutamic acid in a family with Ehlers-Danlos syndrome type IV. An unaffected family member is mosaic for the mutation

Summary Ehlers-Danlos syndrome type IV, an inherited connective tissue disease, is usually caused by mutations in the gene for type III collagen. Here, we describe a glycine to glutamic acid substitution in a patient with this syndrome. Previous studies had shown that fibroblasts from the patient, his mother and brother secreted a reduced amount of type III collagen and also produced an overmodified form of the protein that was preferentially retained intracellularly. Peptide mapping experiments indicated that the mutation was located within cyanogen bromide peptide 9. This was supported by chemical cleavage analysis and sequencing of cDNA encoding this region. Allele-specific oligonucleotide hybridisation of genomic DNA confirmed that a G to A mutation converted Gly 847 to Glu. The mutation was present in two other affected family members and also in a third, who was clinically unaffected. Further analysis of this unaffected individual revealed reduced mutant:normal ratios in DNA obtained from both blood and hair samples, showing that she was mosaic for the mutation.     

Demographic responses of arctic hares Lepus arcticus placed on two predominantly forested islands in Newfoundland

During January-April 1989. we monitored survival, reproduction, and body condition of 19 radio-collared arctic hares Lepus areticus introduced to two predominantly (80%) forested islands. Merchant (66 1 ha) and Burke (82 6 ha), in Placentia Bay, Newfoundland By late April, bone-marrow fat (42 7%) and kidney fat indices were lower than found in populations on the mountain barrens of western Newfoundland However, most island hares gained weight overwinter, and litter sizes (mean. 4 2 in utero) and testis weights (mean, 8 3 g) were as large or larger than recorded from other introduced and natural populations in Newfoundland The distribution of telemetry locations, tracks and feeding sites indicated that hares frequented the scattered barrens (totalling c 30 ha) on both islands in greater proportion than available These results suggest that, in the absence of snowshoe hares and mammalian predators, forested regions interspersed with small patches of barrens can sustain arctic hares     

Enzyme activity in organic solvent as a function of water activity determined by membrane inlet mass spectrometry

Summary Membrane inlet mass spectrometry (MIMS) is introduced as a method for measuring water activity in nonpolar solvents, aqueous solutions and gas phase. The determination of the rate of hydrolysis of diphenyl carbonate by porcine liver esterase as a function of water activity in diisopropyl ether is presented as an example. A linear relationship is found between the enzyme activity and the water activity.     

Modulation of expression of the human gamma interferon gene in E. coli by site-directed mutagenesis

Plasmids expressing 2 forms of human immune interferon (IFN-gamma) in E. coli have been constructed: 1) pIFNTacI which expresses IFN-gamma with an N-terminal amino acid sequence of met-cys-tyr-cys-gln-, and 2) pIFNTacII which is a derivative of pIFNTacI from which the 9 base pairs (bp) coding for the cys-tyr-cys have been deleted. Quantitation of Western blots showed that approximately 10-fold more IFN-gamma was produced in cells harboring pIFNTacII (7.5% of total cellular protein) as compared to pIFNTacI. The IFN-gamma expressed in E. coli pIFNTacII is biologically active and routinely recoverable at 10(9) units per liter. When examined microscopically, IPTG induced E. coli harboring either plasmid construction contains prominent cytoplasmic inclusion bodies.     

Human glyceraldehyde-3-phosphate dehydrogenase: mRNA levels and enzyme activity in developing muscle.

Analysis of human glyceraldehyde-3-phosphate dehydrogenase mRNA revealed that levels in adult skeletal muscle are 12-fold greater per microgram of polyadenylated RNA than in fetal skeletal muscle, whereas in cardiac muscle RNA levels were about equal in fetal and adult tissue. The mRNA levels correlate well with glyceraldehyde 3-phosphate dehydrogenase enzyme activities. There was no evidence for fetus- or tissue-specific forms.     

Phosphoethanolamine and phosphocholine transferases in gray matter and white matter from developing rat brain

We have studied the activities of 2′,3′-cyclic nucleotide 3′-phosphohydrolase, 1,2-diacylglycerol: CDPethanolamine phosphoethanolamine transferase (EC 2.7.8.1), and 1,2-diacylglycerol: CDPcholine phosphocholine transferase (EC 2.7.8.2) in developing rat brain gray matter and white matter. The specific activity of cyclic nucleotide phosphohydrolase was 5–8 fold higher in white matter than in gray matter at all ages. No significant changes were observed during development. The specific activity of phosphocholine transferase was 2 to 3 fold higher than phosphoethanolamine transferase at all ages both in gray and white matter. Both phosphocholine transferase and phosphoethanolamine transferase increased more than 2 fold in specific activity between 14 and 90 days of age. The total activity of phosphocholine transferase also showed an increase during development. The apparentK _m values for nucleotides and dicaprin were similar in gray matter and white matter. Except for lowK _m values for nucleotides at 14 days of age, no significant changes were observed during development. Changes in rates of glycerophospholipid synthesis may be partly due to the specific activities of these enzymes but are also determined by the quantities of substrates and inhibitors and by affinities for the substrates. Special Issue dedicated to Dr. Eugene Kreps.