PEPTIDES AS NEUROTRANSMITTERS IN VASCULAR AUTONOMIC NEURONS

1. Neuropeptides are present in the majority of autonomic neurons projecting to blood vessels, where they are co-localized with non-peptide transmitters and sometimes with other peptides. 2. Neuropeptides are released from vasoconstrictor and vasodilator nerve terminals after high frequency stimulation (>2–5 Hz) with trains of impulses. 3. Neuropeptides can have potent post-synaptic effects on vascular tone, but often these effects are restricted to selected regions of the vasculature. 4. Post-synaptic effects of neuropeptides tend to be more slowly-developing and more long-lasting than those of non-peptide transmitters. 5. Autonomic vasoconstrictor and vasodilator responses often have multiple phases, with the faster phases being mediated by non-peptide transmitters and the slower phases mediated predominantly by one or more neuropeptides. 6. Some neuropeptides do not seem to have post-synaptic effects in a particular vascular bed, but can have presynaptic actions on neurotransmitter release. 7. Neuropeptides form an important component of the repertoire of neurotransmitters used by vascular autonomic neurons to regulate regional blood flow in response to a range of physiological stimuli.     

A community-based epidemiologic study of health sequelae of exposure to hydrofluoric acid.

An accident at an oil refinery in Texas City, Texas, released around 40,000 lb of hydrogen fluoride, exposing the community to the highly toxic and corrosive substance. A population-based epidemiologic study was conducted to evaluate the impact of the accident on the health of the community. Exposure assessment was done using a multipronged approach through a door-to-door survey of 10,811 individuals. A symptom survey resulting in 1994 completed interviews was conducted with a stratified random sample selected from the exposure study database. The sampling was balanced with respect to age, gender, and predisposition across the three ordinal exposure categories. The results show a strong dose relationship (P < 10(-4)) between the exposure and symptoms reported following the accident and 2 years later, most notably breathing and eye symptoms. However, substantial improvement in health was reported over the 2-year period regardless of the level of exposure. Problems of recall bias and behavioral sensitization are considered and it is recognized that the study may have overestimated the effect. It is also recognized that the study may not have completely unraveled the relative importance of exposure and host response in health outcome, since the two were probably conflated in the exposure measure. Nevertheless, the independence of predisposition and reported level of exposure, the magnitude of effect and its consistency, the unmistakable dose response, the large sample size, and the mutual corroboration of various findings make it difficult to dismiss the interpretation that the hydrofluoric acid exposure indeed caused health problems in the community that continued for at least 2 years after the accident.     

Drug mixture which improves survival of ischemic rabbit epigastric skin flaps

The chief aim of this study was to maximize flap survival by counteracting the pathophysiological changes occurring during ischemia-reperfusion. Rabbit epigastric skin flaps given 21 hours of ischemia were infused intra-arterially with selected drugs at the start of reperfusion. Compared with control infused ischemic flaps, which had a 33% survival rate on day 7 post-ischemia, significant improvement was found with vasodilators nitrendipine (61%) and prostacyclin (65%) and the thrombolytic agent urokinase (65%); marginal improvement with the free radical scavenger desferrioxamine (53%); but no change with streptokinase (44%), heparin (21%), and ATP-MgCl₂ (35%). A drug mixture comprising all of these agents except streptokinase and urokinase produced 87% survival, suggesting an additive effect. Biochemical assays on skin homogenates and blood implicated oxygen free radicals, neutrophil infiltration, and thromboxane in flap failure. These results imply that multiple factors are responsible for ischemic flap failure and that a mixture of drugs needs to be infused to counteract all of the detrimental changes. © 1994 Wiley-Liss, Inc.     

The treatment of late post-traumatic orbital deformities

Trauma to the orbital region may result in fractures of the bony orbit, displacement of which gives rise to malposition of the eye and diplopia. If initial treatment is not feasible or is unsuccessful, later correction may be achieved by osteotomy or reduction and stabilisation of the bony fragments, often with bone grafts. Displaced medial or lateral canthi may need to be repositioned, where feasible in an overcorrected position. Where bone grafts are necessary, the skull is now favoured as the best donor site.     

Gastrin: growth enhancing effects on human gastric and colonic tumour cells

Two colorectal (HT29, LoVo) and one gastric (MKN45) human tumour cell lines were examined for their in vitro trophic response to human gastrin-17. MKN45 and HT29 responded by increased 75Se selenomethionine uptake to exogenous gastrin (139 +/- 5.5% and 123 +/- 3% of control values respectively) whereas LoVo showed no significant response to this hormone. When these same cell lines were grown as xenografts in nude mice, similar responses were seen to exogenously administered human gastrin-17 (10 micrograms mouse-1 day-1, subcutaneous injection). MKN45 xenografts showed a greater response to continuously administered gastrin (osmotic mini-pumps, (10 micrograms mouse-1 day-1) when compared to the same dose given via a subcutaneous bolus injection. The hormone-treated xenografts had a two-fold increase in tumour cross-sectional area and growth rate when compared to saline-treated controls. Dose-response studies revealed that 0.4 micrograms gastrin mouse-1 day-1 appeared to be the minimally effective dose. As gastric and colorectal tumour cells show a trophic response to gastrin, antagonists of the gastrin receptor may prevent this effect causing tumour stasis. The gastric tumour cell line, MKN45, is gastrin-responsive and would be an ideal model for screening potent receptor antagonists.     

DQ Wa gives rise to a DQβ restriction fragment pattern indistinguishable from that of the DQw3.2 sub-type Of DQw3

DQ beta restriction fragment patterns have been obtained from five DRw8 cell lines homozygous for the null DQ allele, DQWa. The enzymes Bgl II, Bam HI and Pvu II generate DQ beta patterns which are indistinguishable from those obtained from cell lines homozygous for DQw3.2.     

Cell sizing in chronic lymphoproliferative disorders: an aid to differential diagnosis.

AIMS: To determine if leucocyte volume distribution analysis (LVDA), obtained using a Coulter Counter Model S Plus IV, can be used to aid differentiation of chronic lymphoproliferative disorder (CLPD) subtypes. METHODS: Mean lymphocyte volume and lymphocyte distribution width were measured on each patient (n = 90) using a hard copy of an amplified LVDA histogram. The mean lymphocyte volume was taken as the mean of the values on either side of the peak at half maximum height. The lymphocyte distribution width was taken as the range of cell values between the two values used to calibrate the mean lymphocyte volume. A template showing typical histograms from commonly occurring CLPD was also produced on an acetate sheet. This was used to examine the histogram from each new patient to evaluate its usefulness as an alternative to the calculation of mean lymphocyte volume and lymphocyte distribution width. RESULTS: Mean lymphocyte volume and lymphocyte distribution width were significantly higher in B cell lymphocytic leukaemia of mixed cell type (B CLL/PL), B cell non-Hodgkin's lymphoma with peripheral blood spill, hairy cell leukaemia and T cell prolymphocytic leukaemia than in B cell chronic lymphocytic leukaemia (B CLL). The mean lymphocyte volume, but not the lymphocyte distribution width, was also significantly higher in T cell chronic lymphocytic leukaemia than in B CLL. The template gave an immediate preliminary indication of possible subtype(s) of disorder and could be used as an alternative to measurement of mean lymphocyte volume and lymphocyte distribution width. CONCLUSIONS: Electronic haematology analysers producing an LVDA provide a useful, cost effective cell sizing analysis which can aid the differentiation of subtypes of CLPD.     

Common bile duct calculi: updated experience with dissolution with methyl tertiary butyl ether

The authors describe their experience with methyl tertiary butyl ether (MTBE) in a larger series of patients than previously reported in order to acquaint physicians with both its effectiveness for dissolution of common bile duct calculi and the limitations of its use. Ten patients with 13 biliary calculi underwent percutaneous stone dissolution treatment with the experimental cholesterol solvent, MTBE. Three stones completely dissolved within 30 minutes, seven were reduced in size, and three were visibly unaffected. All stones not completely dissolved were easily extracted by means of a stone basket except for one in a patient taken to surgery. Although MTBE perfusion is an effective technique for management of biliary calculi, practitioners should be aware that its use is quite time consuming and its odor difficult to control.     

Cortical potentials related to voluntary and passive finger movements recorded from subdural electrodes in humans

Movement-related potentials were recorded from subdural electrodes placed on the precentral and postcentral cortex in 3 patients undergoing operation for intractable epilepsy. With self-initiated index finger movement, a negative potential of 25 to 50 microvolts in amplitude, preceding onset of the electromyographic activity by 60 to 95 ms (or onset of movement by 150 to 230 ms), was recorded from the hand somatosensory postrolandic area in all 3 patients. A similar potential preceding the movement was recorded from the precentral hand motor area in one subject who was the only patient in whom the precentral electrodes were placed on the hand motor area. Following active and passive movements, a clearly defined positivity (18 to 32 ms after a photometer trigger) that reversed phase across the central fissure was recorded. The premovement potentials are most probably generated by pyramidal tract neurons and motor-function-related neurons located in the post- and prerolandic areas. The postmovement positivity is most probably due to short-latency kinesthetic reafferent activation of the posterior bank of the central fissure (equivalent to P2 of the somatosensory evoked potentials).     

Sexual experience and use of contraception among young adults in Latin America.

Although a formal public health surveillance system has not yet been established in Latin America to document the attitudes of young people toward sex education, sexual activity, and contraception and their behaviors in these areas, representative data are available from 12 household-based Young Adult Reproductive Health Surveys conducted in seven countries since 1985. The surveys indicate that the rate of sexual experience before marriage or consensual union for males is much higher than that for females, and first sexual experience occurs at a younger age for males than for females. However, from 34% to 90% of females 20-24 years of age report having had premarital sexual relations. No more than 41% of females and 31% of males report that they or their partner used contraception at first sexual experience. Less than one-third of both young men and young women could identify the most fertile period during the menstrual cycle. The results of such surveys have provided program officials and policymakers with data to plan, implement, and evaluate interventions targeted for young adults.