Volume regulation by flounder red blood cells in anisotonic media

The nucleated high K, low Na red blood cells of the winter flounder demonstrated a volume regulatory response subsequent to osmotic swelling or shrinkage. During volume regulation the net water flow was secondary to net inorganic cation flux. Volume regulation the net water flow was secondary to net inorganic cation flux. Volume regulation after osmotic swelling is referred to as regulatory volume decrease (RVD) and was characterized by net K and water loss. Since the electrochemical gradient for K is directed out of the cell there is no need to invoke active processes to explain RVD. When osmotically shrunken, the flounder erythrocyte demonstrated a regulatory volume increase (RVI) back toward control cell volume. The water movements characteristic of RVI were a consequence of net cellular NaCl and KCl uptake with Na accounting for 75 percent of the increase in intracellular cation content. Since the Na electrochemical gradient is directed into the cell, net Na uptake was the result of Na flux via dissipative pathways. The addition of 10(-4)M ouabain to suspensions of flounder erythrocytes was without effect upon net water movements during volume regulation. The presence of ouabain did however lead to a decreased ration of intracellular K:Na. Analysis of net Na and K fluxes in the presence and absence of ouabain led to the conclusion that Na and K fluxes via both conservative and dissipative pathways are increased in response to osmotic swelling or shrinkage. In addition, the Na and K flux rate through both pump and leak pathways decreased in a parallel fashion as cell volume was regulated. Taken as a whole, the Na and K movements through the flounder erythrocyte membrane demonstrated a functional dependence during volume regulation.     

INVESTIGATION OF SECONDARY STRUCTURES AND MACROMOLECULAR INTERACTIONS IN BACTERIOPHAGE P22 BY LASER RAMAN SPECTROSCOPY

Laser Raman spectra of the DNA bacteriophage P22 and of its precursor particles and related structures have been obtained using 514.5-nm excitation. The spectra show that P22 DNA exists in the B form both inside of the phage head and after extraction from the phage. The major coat protein (gp5) contains a secondary structure composed of 18% α-helix, 20% β-sheet and 62% irregular conformations. The scaffolding protein (gp8) in the phage prohead is substantially richer than gp5 in α-helical content. Among the amino acid residues which give prominent Raman lines, the spectra show that tryptophans are exposed to solvent and most tyrosines are hydrogen bonded to positive donor groups. The above features of phage DNA and protein structures are nearly invariant to changes in temperature up to 80°C, indicating a remarkable thermal stability of the phage head and its encapsulated DNA.     

Measurements of glycolytic intermediates during the onset of thermogenesis in the spadix of Arum maculatum

1. This work was done to compare the amounts of glycolytic intermediates in the club of the spadix of Arum maculatum L. at an early stage (α) of development, immediately prior to the increase in glycolysis (pre-thermogenesis), and at the peak of the rapid glycolysis (thermogenesis).2. Glucose 1-phosphate, glucose 6-phosphate, fructose 6-phosphate, 3-phosphoglycerate, 2-phosphoglycerate, phosphoenolpyruvate and pyruvate were measured. The results indicate that at all the above stages of club development the reactions catalysed by phosphoglucomutase, glucosephosphate isomerase, phosphoglycerate mutase and enolase were close to equilibrium, but those catalysed by phosphofructo-kinase and pyruvate kinase were considerably displaced from equilibrium.3. The amounts of the above compounds per club increased 5-fold between α stage and pre-thermogenesis but the relative amounts remained unchanged. When glycolysis increased by more than 50-fold at thermogenesis, the amount of fructose 1,6-diphosphate per club rose, but no changes were detected in the amounts per club of any of the other compounds listed above. These results are discussed in relation to the control of glycolysis.     

A study of prostaglandin F2α as the luteolysin in swine: III effects of estradiol valerate on prostaglandin F, progestins, estrone and estradiol concentrations in the utero-ovarian vein of nonpregnant gilts

Polyvinyl catheters were placed into the right and left utero-ovarian veins and saphenous vein and artery of three control (C) and four estradiol valerate (EV) treated gilts on Day 9 after onset of estrus. The EV treated gilts received 5mg EV/day on Days 11 through 15 after onset of estrus. On Days 12 through 17 utero-ovarian vein blood samples were collected at 15 min intervals from 0700 to 1000 hr and 1900 to 2200 hr and single samples were taken at 1100 and 2300 hr. Peripheral blood samples (saphenous vein or artery) were taken at 0700, 1100, 1900 and 2300 hr from Day 12 until the control gilts returned to estrus or until Day 25 for EV treated gilts and used to measure plasma steroid hormone concentrations. Utero-ovarian vein prostaglandin F (PGF) concentrations (ng/ml, n=1,177) were measured by RIA. Status (control EV treated gilts) by day interactions were detected (P=.10). Curvilinear day trends were detected for plasma PGF concentrations in control (P<.01) but not EV treated gilts. PGF concentrations ( ) for control and EV treated gilts were 1.20 ± 2.08 and .26 ± .84 ng/ml, respectively. PGF peaks (concentrations greater than + 2 S.D.) occured with greater frequency in control gilts (X² = 4.87; P<.05). The interestrus interval ( ) for control and treated gilts was 19.0 ± .6 and 146.5 ± 74.8 days, respectively. Data indicate that estradiol valerate may exert its luteotrophic effect by preventing PGF release from the uterus.     

Mortality from coronary heart disease and stroke in relation to degree of glycaemia: the Whitehall study.

In the Whitehall study of 18 403 male civil servants aged 40-64 years the 10 year mortality rates from coronary heart disease and stroke showed a non-linear relation to two hour blood glucose values, with a significantly increased risk for glucose intolerant subjects with concentrations above the 95th centile point (5.4-11.0 mmol/l; 96-199 mg/100 ml) and for diabetics (blood glucose greater than or equal to 11.1 mmol/l; greater than or equal to 200 mg/100 ml). Multiple logistic analysis showed that between one half and three quarters of the relative risks for deaths from coronary heart disease and stroke were "unexplained" by between group differences in risk factors such as age, blood pressure, obesity, smoking, cholesterol concentration, and electrocardiographic abnormalities. Within the glucose intolerant and diabetic groups the risk factors most strongly related to subsequent death from coronary heart disease were age and blood pressure, with less consistent relations for smoking, cholesterol concentration, and obesity. This study confirms the importance of hypertension as a cardiovascular risk factor in groups with glucose intolerance and diabetes, and this may have important preventive implications.     

Herpes simplex virus type 1 entry through a cascade of virus-cell interactions requires different roles of gD and gH in penetration.

We examined the entry process of herpes simplex virus type 1 (HSV-1) by using infectious virus and previously characterized noninfectious viruses that can bind to cells but cannot penetrate as a result of inactivation of essential viral glycoprotein D (gD) or H (gH). After contact of infectious virus with the cell plasma membrane, discernible changes of the envelope and tegument could be seen by electron microscopy. Noninfectious virions were arrested at distinct steps in interactions with cells. Viruses inactivated by anti-gD neutralizing antibodies attached to cells but were arrested prior to initiation of a visible fusion bridge between the virus and cell. As judged from its increased sensitivity to elution, virus lacking gD was less stably bound to cells than was virus containing gD. Moreover, soluble gD could substantially reduce virus attachment when added to cells prior to or with the addition of virus. Virus inactivated by anti-gH neutralizing antibodies attached and could form a fusion bridge but did not show expansion of the fusion bridge or extensive rearrangement of the envelope and tegument. We propose a model for infectious entry of HSV-1 by a series of interactions between the virion envelope and the cell plasma membrane that trigger virion disassembly, membrane fusion, and capsid penetration. In this entry process, gD mediates a stable attachment that is likely required for penetration, and gH seems to participate in fusion initiation or expansion.     

Amplified cellular oncogenes in neoplasms of the human central nervous system.

Significant advances have recently been made in a number of areas concerning central nervous system (CNS) neoplasia. Particularly salient are the following: (1) gene amplification is related to increasing grade of human glioma malignancy and occurs in approximately 40% of the most common and most malignant variety of glioma, glioblastoma multiforme (GBM), (2) by far the most commonly amplified gene in glioblastomas is the epidermal growth factor receptor (EGFR) gene, which is amplified in about one third of GBMs, (3) a small percentage of GBMs amplify N-myc or the novel sequence gli, (4) the EGFR gene is rearranged in at least half of gliomas in which it is amplified, and (5) EGFR gene rearrangement results in external domain deletions that yield truncated EGF receptors. Antibodies specific for the mutant EGF receptor fusion junction have been successfully produced and provide stimulating new potential avenues for tumor imaging and therapy. For pediatric CNS neoplasms, only medulloblastoma has been investigated in adequate numbers; a small percentage exhibit amplification of either the N-myc or c-myc genes.     

Inhibition of ovulation in the perfused rat ovary by the synthetic collagenase inhibitor SC 44463.

A new, powerful, synthetic inhibitor of mammalian tissue collagenases and related metalloproteinases is inhibitory to ovulation in perfused rat ovaries. Ovaries of immature rats, primed with 20 IU of eCG, were dissected and perfused with 0.1 micrograms/ml LH and 0.2 mM 3-isobutyl-1-methylxanthine (IBMX) for 20 h. Addition of SC 44463 (N4-hydroxy-N1-[1S [(4-methoxphenyl)methyl]-2-(methylamino)-2-oxoethyl]- 2R-(2-methylpropyl)butane-diamide) at a concentration of 25 nM inhibited ovulation by 55% (9.6 +/- 1.7 ovulations per ovary, mean +/- SEM, compared to a control value of 21.7 +/- 1.7); and 250 nM inhibited ovulation by 75% (5.3 +/- 1.1 ovulations per ovary). We previously showed that the related compound SC 40827 inhibited ovulation by 70% when used at a concentration of 25 microM (Br?nnstr?m et al., Endocrinology 1988; 122:1715-1721). We now show that SC 44463 is 100, 500, and 75 times more powerful than SC 40827 in blocking ovulation, inhibiting action of ovarian interstitial collagenase, and inhibiting action of the small metalloproteinase of the rat uterus, respectively. SC 44463 also inhibits ovarian type IV collagen-digesting activity 50% at a concentration of 18 nM. Ovulation occurs after 9-12 h of perfusion with LH. Compound SC 44463 (25 nM) showed its full inhibitory capacity when added to the medium as late as 7 h after LH, but there was no significant inhibition when it was added at 9 h. This suggests that the major collagenolytic events occur beyond 7 h after stimulation by LH.     

Two Types of Genetic Interaction Implicate the Whirligig Gene of Drosophila Melanogaster in Microtubule Organization in the Flagellar Axoneme

The mutant nc4 allele of whirligig (3-54.4) of Drosophila melanogaster fails to complement mutations in an alpha-tubulin locus, alpha 1t, mutations in a beta-tubulin locus, B2t, or a mutation in the haywire locus. However, wrl fails to map to any of the known alpha- or beta-tubulin genes. The extragenic failure to complement could indicate that the wrl product participates in structural interactions with microtubule proteins. The whirligig locus appears to be haploinsufficient for male fertility. Both a deficiency of wrl and possible loss of function alleles obtained by reverting the failure to complement between wrlnc4 and B2tn are dominant male sterile in a genetic background wild type for tubulin. The dominant male sterility of the revertant alleles is suppressed if the flies are also heterozygous for B2tn, for a deficiency of alpha 1t, or for the haync2 allele. These results suggest that it is not the absolute level of wrl gene product but its level relative to tubulin or microtubule function that is important for normal spermatogenesis. The phenotype of homozygous wrl mutants suggests that the whirligig product plays a role in postmeiotic spermatid differentiation, possibly in organizing the microtubules of the sperm flagellar axoneme. Flies homozygous for either wrlnc4 or revertant alleles are viable and female fertile but male sterile. Premeiotic and meiotic stages of spermatogenesis appear normal. However, in post-meiotic stages, flagellar axonemes show loss of the accessory microtubule on the B-subfiber of outer doublet microtubules, outer triplet instead of outer doublet microtubules, and missing central pair microtubules.