Oculomotor control in calliphorid flies: GABAergic organization in heterolateral inhibitory pathways

In calliphorid Diptera, motor neurons mediating visually evoked head movements can be excited or inhibited by visual stimuli, depending on the directionality of the stimulus and whether it is in the ipsi- or contralateral visual field. The level at which inhibition occurs is of special interest because binocular activation of homolateral tangential neurons in the lobula plate demonstrates that excitatory interaction must occur between the left and right optic lobes. Recordings and dye fillings demonstrate a variety of motion-sensitive heterolateral pathways between the lobula plates, or between them and contralateral deutocerebral neuropil, which provides descending pathways to neck motor centers. The profiles of heterolateral tangential cells correspond to neurons stained by an antibody against gamma-aminobutyric acid (GABA). Other GABA-immunoreactive interneurons linking each side of the brain correspond to uniquely identified motion-sensitive neurons linking the deutocerebral. Additional inhibitory pathways include heterolateral GABAergic descending and ascending neurons, as well as heterolateral GABAergic neurons in the thoracic ganglia. The functional significance of heterolateral GABAergic pathways was tested surgically by making selective microlesions and monitoring the oculomotor output. The results demonstrate an important new attribute of the insect visual system. Although lesions can initially abolish an excitatory or inhibitory response, this response is reestablished through alternative pathways that provide inhibitory and excitatory information to the same motor neurons.

Anti-androgen effects of the aromatase inhibitor, atamestane

Prostatic hyperplasia can be induced in both intact and castrated dogs and in intact cynomolgus monkeys by the administration of androgenic steroids. Estrogenic steroids potentiate this effect in dogs. These changes also can be induced by androstenedione, which increases androgen and estrogen levels. Atamestane (ATA; 1-methyl-3,17-dione-androsta-1,4-diene), a potent aromatase inhibitor, inhibits some of the androstendione-induced effects; however, the nonsteroidal aromatase inhibitor, CGS-16949A, has been reported to decrease serum estradiol levels in adult rats but to have no effect on androgen-dependent organ weights. To examine the mechanisms by which ATA affects the rat prostate, in vivo and in vitro studies were conducted using adult rat ventral prostate (VP). Intact Sprague-Dawley rats were injected daily for 14 days with sesame seed oil, ATA (70 mg/kg/day), finasteride (FIN; 5 mg/kg/day), a 5 alpha-reductase inhibitor, or the combination of FIN plus ATA. A fifth group was castrated (CASTR) on day 1. The mean +/- standard error VP weight of the controls was 350 +/- 19 mg. It was reduced 17% (P < 0.05) by ATA, 29% (P < 0.001) by FIN, 48% (P < 0.001) by FIN plus ATA, and 86% (P < 0.001) by CASTR. The DNA/VP was reduced 22% (not significant) by ATA, 18% by FIN (not significant), 35% (P < 0.01) by FIN plus ATA, and 60% (P < 0.001) by CASTR. More significant changes were observed in RNA and protein. The mRNA for prostatein C3 was reduced by each of the treatments, but only CASTR increased the mRNA for TRPM-2, a marker of apoptosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequential imputation for multilocus linkage analysis

A Monte Carlo method called sequential imputation is proposed for multilocus likelihood computations. This method is most useful in mapping situations where the data consist of large pedigrees with substantial missing information and it is desirable to perform linkage analysis utilizing data from many polymorphic markers simultaneously. A pedigree example with 155 individuals, 9 loci, and 155,520 haplotypes is used for illustration.

Asymptotic theory for gene mapping

In genetic linkage mapping, the precision of the location estimate depends on both the number of individuals and the number of markers. Convergence rates and limit laws are established for several situations in which the number of markers depends on the sample size. Practical implications of the results are discussed.

Effects of 4-MAPC, a 5 alpha-reductase inhibitor, and cyproterone acetate on regrowth of the rat ventral prostate

Inhibitors of 5 alpha-reductase activity cause less involution of the rat ventral prostate (VP) than does castration. Studies were conducted in adult Sprague Dawley rats to evaluate the effects of a potent 5 alpha-reductase inhibitor, 4-MAPC, and the antiandrogen, cyproterone acetate (CA), on DNA synthesis and apoptosis. In experiment 1, VP weight fell 33%, 53%, and 83%, and DNA per ventral prostate was reduced 24%, 46%, and 71%, by 4-MAPC, CA, and castration, respectively. In experiment 2, adult rats were castrated, and the VP involuted for 7 days prior to 3 daily injections of testosterone propionate (TP; 1 mg/kg/d) +/- 10 mg/kg/d of 4-MAPC or CA. 3H-thymidine incorporation into VP DNA was increased in castrated animals treated with TP, and 4-MAPC and CA reduced uptake. In experiment 3, animals were treated for 14 days with the same protocol as that used in experiment 2. VP weight was increased in all animals treated with TP when compared with castration, and was reduced by both 4-MAPC and CA. DNA in rats treated with TP was similar to that in intact animals. DNA was not reduced by 4-MAPC, but was reduced by CA. The mRNA for TRPM-2, a marker of apoptosis, was increased only in untreated castrated rats. It appears that CA has a greater inhibitory effect than 4-MAPC on DNA synthesis. A major reason why castration reduces DNA more than either 4-MAPC or CA is that neither of these agents was able to increase programmed cell death to the degree seen with castration.

Infective endocarditis of the pulmonary valve following pulmonary artery catheterisation

The risk of infective endocarditis following pulmonary artery catheterisation in patients with sepsis remains unquantified. Although catheter-induced endocardial and valvular injury are well recognised, valve infection is rare. A case of mixed pulmonary valve endocarditis associated with the use of a pulmonary artery catheter (PAC) in a patient with multisystem failure following liver trauma is described. This illustrates that diagnosis of infective endocarditis in critically ill patients can be difficult because concurrent illness and therapy may mimic or mask the usual presenting signs. The value of transoesophageal echocardiography in this context is emphasised.

Effects of finasteride on the rat ventral prostate

The objectives of this study were to compare changes in the ventral prostate (VP) of young adult Sprague Dawley rats after 28 days of treatment with finasteride (F), a potent 5 alpha-reductase inhibitor, with those caused by castration (Cx). VP concentrations of DHT were reduced to 20.2% and 6.6% of controls (1,947 +/- 207 pg/VP, mean +/- SE) by F (5 or 20 mg/kg/day) and to 2.6% of controls by Cx. VP weights were reduced 49% and 54% by F and 88% by Cx. DNA/VP fell 25% and 15% with F treatment and 72% after Cx, whereas RNA and protein/VP were reduced 37-51% by F and 91-93% by Cx. The RNA/DNA and the protein/DNA ratios fell to 30-36% of controls after F treatment and to 70% of controls after Cx. The mRNA concentrations of the C3 subunit of prostatein 28S ribosomal RNA fell after treatment with F (5 mg/kg/day) and after Cx, whereas the mRNA for TRPM-2, an androgen-suppressed protein associated with apoptosis, was increased only after castration. To examine further the effects of F on the rate of DNA synthesis, 7-day regressed adult rats were treated for 3 days with testosterone propionate +/- F, and incorporation of 3H-thymidine in minced ventral prostates was determined. F inhibited 3H-thymidine incorporation. We conclude that Cx causes a greater reduction in cell number/VP and a greater reduction in RNA and protein cell than F and that the differences between F treatment and castration probably result from differences in prostatic concentrations of T.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequential imputation and multipoint linkage analysis

A novel Monte Carlo method for linkage analyses involving large pedigrees and many polymorphic loci is introduced. Issues related to the efficiency of the method are discussed.

Importance sampling. I. Computing multimodel p values in linkage analysis

In linkage analysis, when the lod score is maximized over multiple genetic models, standard asymptotic approximation of the significance level does not apply. Monte Carlo methods can be used to estimate the p value, but procedures currently used are extremely inefficient. We propose a Monte Carlo procedure based on the concept of importance sampling, which can be thousands of times more efficient than current procedures. With a reasonable amount of computing time, extremely accurate estimates of the p values can be obtained. Both theoretical results and an example of maturity-onset diabetes of the young (MODY) are presented to illustrate the efficiency performance of our method. Relations between single-model and multimodel p values are explored. The new procedure is also used to investigate the performance of asymptotic approximations in a single model situation.

Efficient methods for computing linkage likelihoods of recessive diseases in inbred pedigrees

Traditional methods for computing linkage likelihoods can be infeasible for data that involve considerable inbreeding and missing information, characteristics of large pedigrees affected by rare recessive diseases. For this type of data, we propose alternative procedures that can efficiently provide good approximates of linkage likelihoods. These approximation procedures are constructed based on a new mathematical representation of the multiloci inheritance model. Instead of representing each person by a single variable, the genotype, the disease gene alleles, and the marker alleles are taken as separate variables. This allows us to break down the computations into manageable pieces. This new representation is also potentially useful for multipoint mapping.

Anaesthesia, movement and emesis

One hundred and eighty-two women undergoing dilatation and curettage were allocated randomly to receive premedication comprising temazepam, papaveretum-hyoscine or placebo. The temazepam recipients reported significantly fewer episodes of postoperative nausea. Movement was blamed by 66% of patients who identified a cause for nausea. These patients had higher scores on a motion sickness susceptibility questionnaire and were more likely to have been treated previously for nausea or vomiting. It may be possible to identify susceptible patients before surgery.

Thrombolytic therapy in canine pulmonary embolism. Comparative effects of urokinase and recombinant tissue plasminogen activator

We compared thrombolytic and pulmonary hemodynamic effects of recombinant tissue plasminogen activator (rtPA) and urokinase (UK) in canine micropulmonary thromboembolism. Dogs were embolized with radioactive autologous blood clot to increase mean pulmonary artery pressure (from 13 to 34 mm Hg, p less than 0.005) and decrease cardiac output (2.5 to 1.6 L min, p less than 0.005). Four groups of six dogs were treated. We employed two doses of UK, 30,000 U/kg (UK30) and 60,000 U/kg (UK60), and two doses of rtPA, 1 mg/kg (rtPA1) and 2 mg/kg (rtPA2). Drugs were infused over 15 min. Rate and extent of pulmonary thrombolysis were assessed by continuously counting over both lung fields with a gamma camera. Compared with treatment with UK, both rtPA regimes significantly increased thrombolysis. Mean total pulmonary thrombolysis was 14 and 23% with UK30 and UK60, respectively, and 35 and 43% with rtPA1 and rtPA2. Corresponding to the increased thrombolysis, pulmonary hemodynamics improved most with rtPA. From 90 min to 3 h, pulmonary artery pressure was significantly lower with both rtPA regimes than with either UK regime. These results indicate, at least in the model employed, that compared with treatment with UK, pulmonary thrombolysis and corresponding hemodynamic improvement are greatest with rtPA.

Prostatein C3-mRNA: a sensitive marker of androgen-responsiveness in prostate explant cultures

Prostatein is an androgen-dependent protein which is secreted by the rat ventral prostate. To determine if prostatein or its mRNA were responsive to androgen in vitro, prostate explants were cultured in media containing 0 or 25 nM dihydrotestosterone (DHT), estradiol (E2), or cortisol (F). Prostatein concentrations in medium were measured by radioimmunoassay at 2 and 4 days and in homogenates at 4 days. They were not changed significantly by any of these steroids. The concentration of the mRNA for the C3-subunit of prostatein was determined by dot hybridization at 0, 2, 4, 6, and 8 days. It was decreased significantly by 2 days when compared with explants cultured in the presence of DHT and significant differences persisted through 8 days. In conclusion, quantitation of the mRNA for the C3-subunit of prostatein in short-term cultures of ventral prostate explants appears to be more sensitive to changes in androgen concentration than does measurement of prostatein, per se. Prostatein C3-mRNA may be a useful marker for in vitro studies of androgen agonists and antagonists.

How medical professionals evaluate expressions of probability

Qualitative expressions of probability, such as "likely," have different numerical meanings to different people, which can lead to misunderstanding among physicians and between physicians and patients. In a study conducted through a nationwide interactive computer network based at Massachusetts General Hospital, we gathered information on the meaning of common expressions of probability. Three groups of medical professionals assigned percentage values to 12 expressions of the probability that a given symptom would appear in a patient with an unspecified disease. The median values assigned to these expressions by physicians, medical students, and other professionals were almost the same. Comparisons of the means for 7 of these 12 expressions with those found in an earlier study by other investigators showed that they were quantified in the same order, although they had not been assigned the same numerical values. This degree of agreement among professionals and between studies is encouraging for the future prospects of codifying the meaning of such expressions. The variation among five studies in the mean values assigned to 37 expressions in the medical literature and the variation among individual opinions show that such codification is necessary. In the meantime, the average numerical values presented here for various qualitative expressions of probability could well be used to enhance communication among medical professionals.

Effect of chlorpromazine on cyanide intoxication

Previous reports from our laboratory indicated that prophylactic protection against cyanide intoxication in mice can be enhanced by administration of chlorpromazine when it is given with sodium thiosulfate. The mechanism of potentiation of sodium thiosulfate by chlorpromazine was studied alone and in combination with sodium nitrite. Although chlorpromazine was found to induce a hypothermic response, the mechanism of enhancement of the antagonism of cyanide by chlorpromazine does not correlate with the hypothermia produced. Various other possible mechanisms were investigated, such as rate of methemoglobin formation, enzymatic activity of rhodanese and cytochrome oxidase, and alpha-adrenergic blockade. The alpha-adrenergic blocking properties of chlorpromazine may provide a basis for its antidotal effect, since this protective effect can be reversed with an alpha-agonist, methoxamine.

Properties of CRF from normal and Brattleboro rat median eminence

Most of the corticotrophin-releasing factor (CRF) activity of normal rat median eminence (ME) extract binds to a neurophysin affinity column. The bound material contains the large and small factors, which we have previously demonstrated to be required together for full activity. Most of the CRF activity of Brattleboro rat ME extract, which contains as much CRF activity as the ME extract of a normal rat, does not bind to a neurophysin affinity column. The CRF activity of Brattleboro rat ME extract resides entirely in a large molecule as determined by Sephadex G-25 chromatography. The different properties of Brattleboro and normal rat CRF suggest that the CRF activity in the Brattleboro rat may result from a substance which is different from that in a normal rat.

Isolation, structure and synthesis of a heptapeptide with in vitro ACTH-releasing activity from porcine hypothalamus

Significant CRF activity was found in a fraction with Rf = 0.82-0.7 or VE/VT = 0.41-0.48 obtained by gel filtration of acid extracts of pig hypothalami on Sephadex G-25. The activity of this fraction decreased markedly during subsequent purification, particularly in the last two steps. From this fraction, a heptapeptide with significant ACTH releasing activity in vitro, was isolated in pure state, and its amino acid sequence was established as H-Phe-Ile-Tyr-His-Ser-Tyr-Lys-OH. This heptapeptide was synthesized by solid phase methods. The CRF activity of synthetic heptapeptide in vitro was low but could be potentiated by a cofactor fraction from rat hypothalamic extract.

A model for the study of the oral administration of peptide hormones

The intragastric administration of lysine vasopressin (LVP) to rats is used as a model to study the biological activity of orally administered peptide hormones. Using a modification of the antidiuretic assay of Sawyer, LVP given by stomach tube caused a significant antidiuresis that was dose dependent in doses of 300 to 2000 mU. The simultaneous administration of the protease inhibitor, Trasylol, increased the antidiuretic effect of LVP. The synthetic peptide (1-deamino, 4 valine)-8-D-arginine-vasopressin also caused a dose-dependent prolonged and significant antidiuresis. No pressor effect was observed after intragastric administration of LVP in doses up to 40 U/rat. We are now using this model to test other procedures for enhancing the activity of lysine vasopressin administered in the gastrointestinal tract such as encapsulation into liposomes. The information gained with vasopressin will then be applied to insulin with the ultimate goal of making oral administration practical.