Captopril in renovascular hypertension: long-term use in predicting surgical outcome.

The angiotensin converting-enzyme inhibitor captopril was used as long-term preoperative treatment in a series of hypertensive patients with unilateral renal arterial disease. There were immediate and sustained falls in plasma angiotensin II and aldosterone concentrations, with converse increases in circulating renin and angiotensin I. In patients with sodium and potassium deficiency and secondary aldosterone excess before treatment captopril corrected the sodium and potassium deficits; in these cases the initial hypotensive response was profound but the later effect was less pronounced. When sodium and potassium state was initially normal it remained unchanged during captopril treatment, while the full hypotensive effect took up to three weeks to be attained. The immediate, but not long-term, falls in arterial pressure with captopril were proportional to the immediate decrements of plasma angiotensin II. Nevertheless, while the immediate blood-pressure reduction with captopril variously overestimated and underestimated the eventual surgical response, the absolute blood-pressure values during long-term captopril related well with those after operation. Pretreatment plasma renin and angiotensin II concentrations, while closely predicting the immediate captopril response, are fallible guides to surgical prognosis. In contrast, long-term treatment with converting-enzyme inhibitors may provide an accurate indication of surgical outcome.     

A comparison of the ability of serum and monoclonal antibodies to gastric inhibitory polypeptide to detect immunoreactive cells in the gastroenteropancreatic system of mammals and reptiles

Summary A monoclonal antibody raised to gastric inhibitory polypeptide (GIP) has been compared with conventional rabbit and guinea-pig antisera to GIP. Four staining methods were tested and of these the peroxidase antiperoxidase (PAP) method proved to give the best results with both the mouse and rabbit antibodies. The monoclonal antibody, when used to stain pancreatic tissue, gave negative results whereas a distinct population of gut endocrine cells was readily demonstrable, suggesting that GIP is not a constituent of the mammalian pancreas. The monoclonal antibody was found to be the most sensitive for immunocytochemistry achieving the titre of 1:10⁶ in rat gut. A C-terminal specific antibody, with a high affinity and avidity to GIP, it was clearly the preferred antibody for immunocytochemical studies.     

Is exercise good for high blood pressure?

Ten men with uncomplicated essential hypertension (mean standing blood pressure 165/109 mm Hg) and 10 normal controls matched for age and weight were studied for the hypotensive potential of moderate exercise. Tests were conducted on a treadmill set to induce a steady heart rate of 120 beats/min and performed over five 10-minute periods separated by three minutes'' rest and finishing with 30 minutes'' sitting quietly in a chair.During exercise the mean systolic pressures were identical in the hypertensive patients and controls (175±SEM 5 mm Hg), the controls therefore sustaining an appreciably greater increase in pressure. During the 30-minute rest period after the tests both the control and hypertensive groups showed a significant and sustained fall in absolute systolic pressures as compared with pre-exercise values (p <0·001), the mean percentage reductions being 22% and 25% respectively.If a fall in blood pressure after exercise is maintained for four to 10 hours, then a “good walk” twice a day might be reasonable treatment for mild hypertension. Studies are continuing to determine the amount of exercise needed and the duration for which the reduction in blood pressure is maintained.     

Developmental patterns of ornithine decarboxylase activity in organogenesis phase rat embryos in culture and in utero

Summary Ornithine decarboxylase activity was measured during organogenesis in rat embryos grown in utero and whole rat conceptuses maintained in an in vitro culture system. Ornithine decarboxylase levels in vivo showed a distinct peak at embryonic age 10.5 d. Despite identical morphology, protein content, crown rump length and numbers of somites cultured embryos displayed a different developmental pattern and possessed less than half the ODC activity of that in vivo. The data suggest that the normal embryonic programming of ODC activity is significantly altered by the culture environment and that further biochemical comparisons of embryos growing in utero and in vitro may be required to evaluate properly the applicability of this technique to detailed studies of teratogenesis and developmental biology. This work was supported by NIH-5-507-RR5359-17 and a 1980 Research Starter Grant from the Pharmaceutical Manufacturers Association Foundation.     

Reversed-phase liquid chromatographic investigation of UV-absorbing low-molecular-weight compounds in saliva

The reversed-phase mode of high-performance liquid chromatography was used to determine the intra- and inter-individual levels of UV-absorbing low-molecular-weight compounds in saliva. Many of the compounds known to occur in serum were also found in saliva; however, concentrations in saliva are lower. Both the intra- and inter-individual levels of these compounds vary significantly; in most cases, the inter-individual variance is 2–3 times the intra-individual variance.

Caffeine and its metabolites in saliva are also reported. A greater number of metabolites were found in the saliva of habitual coffee drinkers. After caffeine was administered orally, paraxanthine, theobromine, theophylline, 1-methylxanthine, and 1-methyluric acid were found in the saliva of an individual who did not drink coffee regularly. In this subject, the serum half-life for caffeine was 3.49 h and the saliva half-life was 3.27 h. The half-life of caffeine in an habitual coffee drinker who had refrained from caffeine products for four days was 4.39 h.     

Diurnal changes in the chilling sensitivity of seedlings

Seedlings of tomato (Lycopersicon esculentum, Mill.) varied diurnally in their sensitivity to chilling temperatures. If chilled near the end of the dark period when they were most sensitive, the time taken to kill half of the seedlings was approximately 3 days, whereas in samples taken 4 hours after the onset of dark, a period of 6 days of chilling was required. Sensitivity dropped rapidly after the onset of the light period. This rhythm was exogenously controlled by the diurnal changes in light, rather than in the temperature. The susceptibility of predawn seedlings could be reduced by exposure to light, by water stress, or by abscisic acid applied to the leaves. However, the subsequent changes in sensitivity to chilling did not correlate with stomatal aperture. Six other chilling-sensitive species showed similar diurnal changes in their chilling sensitivity.     

The control of cellulose microfibril deposition in the cell wall of higher plants

In maize (Zea mays L.) and pine (Pinus taeda L.) seedlings, cellulose microfibril impressions are present on freeze-fractured plasma membranes. It has been proposed that impressions of newly synthesized microfibrils are a record of the movement of terminal synthesizing complexes through the plasma membrane (Mueller and Brown, 1980, J. Cell Biol. 84, 315–326). The association of terminal complexes with the ends of microfibril impressions or with the ends of microfibrils torn through the membrane indicates the orientation of microfibril tips. Unidirectionally-oriented microfibril tips (all pointing in the same direction) are associated with the organized deposition of parallel arrays of microfibrils. Multidirectionally-oriented microfibril tips were observed in a cell in which microfibril deposition was unusually disorganized. Microfibril patterns around pit fields are asymmetric and resemble flow patterns. Unidirectionally-oriented tears are associated with these microfibrils. Although microfibril orientations are deflected around pit fields, the main axis of microfibril orientation is maintained across the surface of the cell. The hypothesis is proposed that the interaction of a flowing plasma membrane with microfibril synthesizing complexes in the plane of the membrane may result in unidirectional deposition and asymmetric microfibril impressions around pit fields.Some of this work has been published in preliminary form (Brown 1979)     

Bean lectins

Summary Single seeds of over 100 bean cultivars were analyzed by two-dimensional electrophoresis. The cultivars could be classified into eight groups by virtue of their G2/albumin electrophoretic patterns: T_G2, S_G2, V_G2, Pr_G2, B_G2, M_G2, P_G2, and Pi_G2, The polypeptide compositions of these types were largely inter-related having particular polypeptides in common. It was possible to correlate the G2/albumin patterns with agglutinating activity of cow and rabbit blood cells as measured by the agglutination ratio (minimum concentration of extract required to agglutinate cow blood cells: minimum concentration of extract required to agglutinate rabbit blood cells). The active lectin polypeptides were identified by extracting lectins from agglutinated erythrocytes and by comparing the qualitative similarities and differences of the G2/albumin patterns and their agglutination activities. A reference catalogue of over 100 bean cultivars giving their phaseolin and G2/albumin electrophoretic patterns, and agglutination ratios is presented.