Experimental electrocoagulation of dog esophageal and duodenal mucosa

The per review system for the assessment of research proposals is widely respected by working scientists. Nevertheless two problems associated with the operation of this system by the US National Institutes of Health are identified. First the scientist has no control over which committee will review an application and it may be considered by a quite inappropriate group. Second analysis of the committee composition suggests that in some of the groups several members are not active scientists and therefore not the "peers" of the applicant.     

Chloramphenicol antibody causing interference in antibody detection and identification tests

Investigation of the serum of three patients with positive antibody detection tests demonstrated the cause in each to be an antibody against chloramphenicol, a bacteriostatic agent used in commercial red blood cell reagents. Washing of these red cells prior to use prevented agglutination. All three examples of anti-chloramphenicol antibody were IgM and were in low titer when tested at room temperature and 37 C in saline. Two of the antibodies bound complement. The possibility of an antibody to an ingredient of the commercial preservative solution should be considered if problems are encountered in tests with unwashed commercial red blood cell reagents.     

Significance of a new type of human fetal hemoglobin carrying a replacement isoleucine replaced by threonine at position 75 )E 19) of the gamma chain

Mating speed of flies which have been aged either in the light, in the dark or in a light-and-dark cycle was measured using two strains, Rochester (R) and Salvador (S), of Drosophila mercatorum. A significant difference in mating tendency depending on the condition of pretreatment was found between R and S strains, while both strains showed a similar pattern of the diurnal rhythm in the light-and-dark cycle. Compared under the same conditions, S flies usually showed a higher mating speed than R flies. Mating speed seems to be affected by at least two different genetic systems. One of them is the genetic system determining absolute speed of mating. Another is the genetic system determining sensitivity to the environmental conditions. There may be considerable differentiation in both systems between R and S strains.     

Simple mathematical models with very complicated dynamics

First-order difference equations arise in many contexts in the biological, economic and social sciences. Such equations, even though simple and deterministic, can exhibit a surprising array of dynamical behaviour, from stable points, to a bifurcating hiearchy of stable cycles, to apparently random fluctuations. There are consequently many fascinating problems, some concerned with delicate mathematical aspects of the fine structure of the trajectories, and some concerned with the practical implications and applications. This is an interpretive review of them.     

Differing effects of the vasodilator drugs, prazosin and diazoxide on plasma renin activity in the dog

1. The effects of intravenous (i.v.) administration of the vasodilator drugs prazosin or diazoxide on blood pressure and plasma renin activity were evaluated in the anaesthetized dog. 2. Prazosin and diazoxide both induced a rapid reduction in the mean arterial pressure to 73% and 75% of control values respectively. 3. Prazosin lowered plasma renin activity to 62% (P less than 0-025) of the control value whereas diazoxide raised plasma renin activity to 178% (P less than 0.05) of the control value. 4. The combination of vasodilatation and low renin activity observed following the administration of prazosin is unique, and may have clinical significance if these factors reduce the vascular complications of hypertension.     

Mortality and some biochemical changes in mink (Mustela vison) given sublethal doses of aflatoxin each day

Two feeding trials were done to study the susceptibility of mink (Mustela vison) to multiple sublethal doses of aflatoxins. In the 1st trial, twenty 3-month-old male mink were divided equally among groups. Each mink in groups 1, 2, 3, and 4 was given a meatball daily that contained 15, 30, 45, or 0 mug of aflatoxins (B1:G1, 40:60), respectively. All mink in group 3 died between the 25th and the 30th days of the feeding trial. Each mink had ingested 1,035 to 1,480 mug of aflatoxins. Four of the mink in group 2 died almost as soon as did mink in group 3. Four mink in group 1 died between 40 and 59 days after the start of the feeding trial. Generally, a marked increase in plasma cholesterol and alkaline phosphatase activity appeared before mink died. The liver from animals that died of aflatoxicosis showed prominent pathologic changes which included hemorrhages and appearance of pink yellow spots. Histopathologic examination of liver from dead mink revealed fatty infiltration, bile duct proliferation, bile stasis, pseudotubular formation, congestion, and fibrosis. The feeding trial was repeated with 20 mink (8 males and 12 females) that were 1.5 to 2 years old. In this instance, 0, 20, 40, and 60 mug of aflatoxins were administered each day. All treated animals, except 1, were dead within 37 days after the experiment started. The survivor was given the lowest dosage of toxins and died after 52 days by which time 960 mug of aflatoxins were consumed. Plasma cholesterol content and alkaline phosphatase activity generally were similar to those observed in younger mink of the 1st feeding trial.     

Cryoimmunoglobulin IgGk with microtubular ultrastructure associated with pyoderma gangrenosum

Based on the hitherto published population data of the human red cell PGM1 and acid phosphatase polymorphisms, the geographical distributions of their gene frequencies were analyzed. As far as the acid phosphatase alleles are concerned, a marked geographical gradient was found as the Pa and Pb alleles showed significant correlations with the mean annual temperatures of the various human biotopes (Pa:r = -0.706; Pb:r = +0.812). Against that, the world distribution of the PGM1 alleles did not show a comparable correlation (PGM1 1:R = +0.063; PGM2 1:R = -0.063). The possible reasons for the distribution pattern of the acid phosphatase alleles are discussed.     

Hemodynamic effects of vasodilator agents in dogs with experimental ventricular septal defects

The ratio of pulmonary to systemic vascular resistance (Rp/Rs) largely determines the amount of left-to-right shunting and pulmonary to systemic flow rat (Qp/Qs) in the presence of a large isolated ventricular septal defect. The possibility that pharmacologic reduction of systemic vascular resistance with alpha-adrenergic receptor blockade or beta-adrenergic receptor stimulation would increase the ratio Rp/Rs, and therefore reduce the ratio Qp/Qs, was studied in dogs in which ventricular septal defects had been surgically created. Administration of phentolamine and phenoxybenzamine caused a 42% reduction in Rs and no reduction in Rp. Qs was unchanged and Qp declined by 24% and the ratio Qp/Qs fell by 32%. Infusion of the beta-adrenergic receptor stimulant isoproterenol also reduced Qp/Qs. However, this was accomplished as a result of an increase in Qs and at the expense of an increase in heart rate. As a decline in the ratio Qp/Qs has been shown to be beneficial to patients with large left-to-right shunts, pharmacologic reduction of systemic vascular resistance may prove to be helpful in treating congestive heart failure in those patients with large left-to-right shunts at the ventricular level who are refractory to the usual decongestive measures.