Testicular endocrine effects of alkane methanesulphonates related to the Leydig cell cytotoxic compound, EDS

A series of compounds structurally similar to the specific Leydig-cell-cytotoxic substance ethane-1,2-dimethanesulphonate (EDS) were examined for Leydig cell toxicity in the rat. Within 48 h of a single injection of butane-2,3-dimethanesulphonate (BDS), propan-1,3-dimethanesulphonate (P-1,3-DS) or propan-1-chloro-2,3-DS (PCDS) there was a reduction in serum and testicular testosterone levels. The serum luteinizing hormone (LH) concentration was reduced following BDS or P-1,3-DS, and Leydig-cell LH receptors (measured by 125I-labelled hCG binding) were reduced by less than 15%, from which it is concluded that these compounds are not selectively toxic to Leydig cells. However, PCDS reduced human chorionic gonadotropin (hCG) binding by greater than 70% and could be considered to be a potential toxin. The effects of hydroxy-ethanemethane-sulphonate (HEMS), 1,5,2,4-dioxadithiepane-2,2,4,4-tetraoxide (cyclic SOSO), PCDS, propan-2,3-DS, alpha-chlorohydrin and cyclohexane-1,2-dimethane-sulphonate were compared with the effects of EDS 7 days after injection. Systemic toxicity, indicated by a loss of body weight, was associated with cyclic SOSO, PCDS and EDS, although only EDS and PCDS reduced both testicular hCG binding and serum and testis testosterone levels consistent with Leydig-cell toxicity. Further studies indicated that the potency of PCDS in reducing testicular hCG binding and serum and intratesticular testosterone levels was similar to that of EDS. However, unlike EDS, PCDS was systemically toxic and also reduced LH, which could at least in part account for changes in testosterone secretion. The experiments confirm the unique cytotoxicity of EDS. Loss of specific Leydig-cell cytotoxicity and an increase in systemic toxicity occurred when the EDS molecule was altered, even if the distance between the alkylating centres was maintained. The mechanism of action of EDS remains elusive.

A stable variant of Simonsiella muelleri with unusual colonial and cellular morphology

The unusual morphology and cellular arrangement of a member of the genus Simonsiella is described. The organism is characterized by the formation of very long trichomes, which can be greater than 1,000 microns in length.

Adaptations of synaptic form in an aberrant projection to the avian cochlear nucleus

Surgical removal of the otocyst in chick embryos induces axons from the contralateral cochlear nucleus (nucleus magnocellularis, NM) to form, in addition to their normal endings in nucleus laminaris (NL), anomalous and persistent functional contacts in the ipsilateral NM (Jackson and Parks, 1988). We have examined how interaction between the abnormal synaptic partners during development influences the form of the axon terminal and its relation to the target neuron. In the light microscope, aberrant axon terminals labeled in vitro with HRP appear to form boutons quite unlike the large calycine endbulbs made by the normal cochlear nerve (CN) endings in NM. In the electron microscope, however, the anomalous endings appear embedded in the NM cells, something never seen normally in NM or NL. Morphometric analyses were performed on electron micrographs from NM and NL in animals aged embryonic day (E) 19 to posthatching day (P) 2 from which the right otocyst had been removed on E3 and in normal control animals. Aberrant endings appose 18% of the circumference of operated NM cells, versus 45% for CN axons in the normal NM at this age. The mean length of membrane apposition for the anomalous NM-to-NM endings was 215% greater than for normal NM-to-NL endings but 54% smaller than that in normal CN endings. These results support the idea that developmental interactions between synaptic partners can influence the form of the contact between the 2 neurons. The results also demonstrate, however, that formation of persistent and functional synapses with NM neurons throughout development is not sufficient to induce any axon to assume the calycine form of a cochlear nerve endbulb.(ABSTRACT TRUNCATED AT 250 WORDS)

Attitudes, knowledge, experience and behaviour related to HIV and AIDS among Zimbabwean social workers

A recent study of Samuels & Boyle (1989) examined knowledge, attitudes, and behaviours of social service team members in Newham, East London in relation to HIV and AIDS. This study extends theirs to investigate social workers, both experienced and in training, in Harare, Zimbabwe, Whilst overall, there appear to be high levels of knowledge and positive attitudes displayed by these social workers, detailed examination of their responses shows gaps in knowledge and ambivalent attitudes and behaviours. These issues should be addressed when planning AIDS training courses.

The tissue distribution in rats of [195mPt]carboplatin following intravenous, intraperitoneal and oral administration

[195mPt]carboplatin has been administered intravenously, intraperitoneally and orally to Wistar rats and the tissue distribution, metabolism, and pharmacokinetics of the drug investigated. The urinary and faecal excretion and toxicity following oral [195mPt]carboplatin administration has also been studied. Virtually identical results have been observed following i.v. and i.p. administration, indicating a rapid absorption of the unaltered compound from the abdominal cavity into the systemic circulation. Thus i.p. administered drug should produce a similar therapeutic response as i.v. administration, but may produce an additional local effect within the peritoneal cavity. Orally administered compound shows a pattern of distribution which is similar to that following parenteral injection for all tissues (except for the increased relative concentration in the stomach tissue), the concentration being lower by a factor of 4-5. However, the overall fraction of the dose retained within the body at 24 h is similar to that following i.v. administration. The toxicity is considerably lower for the orally administered drug compared with i.v. injection. These results clearly show that oral doses could be adjusted to produce a comparable therapeutic effect as i.v. or i.p. doses, and should also result in a higher efficacy against gastric carcinomas than achievable with parenteral administration.

Quantification of urinary 3-hydroxyisovaleric acid using deuterated 3-hydroxyisovaleric acid as internal standard

Deficiency of biotin at the tissue level can be assessed indirectly by measuring the urinary excretion of 3-hydroxyisovaleric acid. This paper describes the application of an improved method of quantifying urinary 3-hydroxyisovaleric acid using unlabeled and uniformly deuterated 3-hydroxyisovaleric acid. These compounds were synthesized by a modification of the lithioacetic acid method for generation of beta-hydroxy acids. Elemental analysis, nuclear magnetic resonance, gas chromatographic and gas chromatographic/mass spectrometric data demonstrated that the compounds are greater than 95% pure. Mass spectrometry confirmed the identity of the unlabeled compound, demonstrated that the deuterated compound is uniformly labeled, and offered insight into the pattern of mass fragmentation. The method for determination of the concentration of 3-hydroxyisovaleric acid in rat urine uses gas chromatographic/mass spectrometric quantification of the di-trimethylsilyl derivative with the deuterated compound as the internal standard. Results provide evidence that this method is more accurate than a previously published method that did not utilize the unlabeled and deuterated standards.

5-HT1A-receptor antagonism: N-alkyl derivatives of (R)-(-)-8,11-dimethoxynoraporphine

Prompted by previous findings that a p-dimethoxy substitution pattern on an aromatic ring permits retention of dopaminergic agonist effects in certain ring systems, catechol derivatives of which are potent dopaminergic agonists, an 8,11-dimethoxy substitution pattern was introduced into the aporphine ring in place of the 10,11-dihydroxy moiety in apomorphine. Acid-catalyzed rearrangement of an appropriate morphine derivative provided the aporphine ring system with retention of the stereochemical integrity of the 6a asymmetric center. The hydroxyl group at position 10 was removed by catalytic hydrogenolysis of its phenyltetrazoyl ether. The methyl ether of the resulting 11-hydroxyaporphine was iodinated in high yield at position 8 with trifluoroacetyl hypiodite. This is the first account of synthesis of an iodinated aporphine derivative. The 8-iodo substituent was replaced with methoxyl by reaction with sodium methoxide and cuprous iodide. Neither the N-methyl target compound 7 nor the N-n-propyl derivative 8 demonstrated dopaminergic nor serotonergic agonism. However, 7 exhibited receptor-binding characteristics and other pharmacological properties suggesting that it may be a 5-HT1A receptor antagonist.

The role of standard roentgenograms in the evaluation of instability of pelvic ring disruption

Anteroposterior pelvic roentgenograms of 154 patients with pelvic ring disruptions were evaluated to assess their value in the determination of pelvic instability. Three different categories of stability were roentgenographically recognizable: (1) stable, characterized by impacted vertical fracture of the sacrum, nondisplaced fracture of the posterior sacroiliac complex, and/or subtle fractures of the upper sacrum evidenced by asymmetry of the sacral arcuate lines; (2) unstable, characterized by hemipelvic cephalad displacement exceeding 0.5 cm, sacroiliac joint diastasis exceeding 1 cm and/or sacral or iliac diastatic fracture exceeding 0.5 cm; and (3) indeterminate (that is, suspicious but not diagnostic of pelvic instability), characterized by cephalad hemipelvic displacement of less than 0.5 cm, sacroiliac joint diastasis less than 1 cm, and/or diastatic fracture of the sacrum or ilium of less than 0.5 cm. Correlation of the standard roentgenographic, computed tomographic, and clinical orthopedic examinations revealed that pelvic stability was accurately evaluated on the standard pelvic roentgenograms in 88% of cases. Disruptions were stable in 70%, unstable in 18%, and suspect in 12% of patients, for whom adjunct roentgenographic and clinical examinations were required. Determination of pelvic stability in the manner described allows immediate identification of patients with a stable or unstable pelvic injury, as well as identification of those with indeterminate stability requiring further clinical or roentgenologic evaluation. Immediate recognition of pelvic instability on standard pelvic roentgenograms obviates the need for additional diagnostic studies that unnecessarily delay the institution of emergency therapeutic measures designed to control associated hemorrhage.

AIDS and the press: an analysis of the coverage of AIDS by Zimbabwe newspapers

An analysis of articles about HIV and AIDS in Zimbabwe newspapers for the period January 1987 to September 1988 reveals several areas of concern. An analysis of coverage before and after a Government campaign designed to increase awareness of issues related to AIDS indicated only a short term increase in press coverage of such issues. Articles were assigned to one of seven content categories: statistics, cure or vaccine, prevention, education and awareness, transmission and risk, counselling and care, and policy and economics. The relative lack of articles on counselling and care and on transmission and risk indicates possible gaps in public awareness of susceptibility to AIDS. There were few articles with a local basis, nor were there any personalized stories. This is likely to encourage feelings of distance and relatively low personal risk. In general, Zimbabwe newspapers show little of the sensationalist and prejudiced accounting of AIDS found in some British press coverage.

Diagnostic radiology. One week prelude to the clinical continuum

A one-week comprehensive program of diagnostic radiology was presented to 205 junior medical students just entering the clinical phase of their education. Course objectives were to familiarize the students with the various imaging modalities and their application to common clinical situations and to introduce an organized approach to interpretation of conventional radiographs. This course's one-week time frame was unique. Various educational activities were employed to allow the large number of students to participate actively in the educational process and to enable them to cope with the intensive presentation of unfamiliar vocabulary, materials, and modalities. Through this course, the students achieved an understanding of the impact of radiologic findings on clinical situations and of the necessity of designing an orderly radiologic workup tailored to patient needs and clinical presentation. Most importantly, they gained a functional knowledge of the decision-making process involved in radiology as well as in clinical medicine.

Induction of aberrant functional afferents to the chick cochlear nucleus

Surgical extirpation of the otocyst on embryonic day (E) 3 in chick embryos prevents formation of the cochlear nerve and results in development of an aberrant axonal projection from the contralateral cochlear nucleus (nucleus magnocellularis, NM) to the deafferented NM. We have studied the morphology of this projection using horseradish peroxidase injections in NM axons and light and electron microscopy. The ability of the projection to activate its target neurons synaptically was assessed by means of extracellular microelectrode recording from in vitro preparations of the chick brainstem. The aberrant projection arises as a vertically directed branch from the contralaterally traveling NM axon at the medial border of nucleus laminaris (NL). This axonal branch forms boutonal endings that may terminate anywhere in NM but are most common in its ventral and medial regions. In our experiments, this projection is not seen on the unoperated side of experimental animals or in normal controls from E11 onward but is found on the operated sides of all experimental animals, including those with bilateral removal of the otocysts. The aberrant projection persists at least from E11 through hatching and has essentially identical features in unilaterally and bilaterally lesioned animals. The endings of the aberrant projection are boutonal in form and, in the electron microscope, exhibit all of the elements associated with normal synapses. Electrophysiological studies confirm that stimulation of the aberrant axons can elicit postsynaptic responses in NM and suggest that these synapses use an excitatory amino acid neurotransmitter.

Generalized eruptive pustular drug rash due to cephalexin

A 38-year-old woman developed a generalized pustular eruption 18 h after taking an oral cephalosporin (cephalexin). After having excluded other possible pustular dermatoses, we concluded that our patient's eruption was drug-induced.

Experience-independent development of dendritic organization in the avian nucleus laminaris

The third-order auditory neurons of the avian nucleus laminaris (NL) have distinct dorsal and ventral dendritic tufts that receive their predominant synaptic input from, respectively, the ipsilateral and contralateral cochlear nucleus. Beginning about embryonic day (E) 14 in the chick and continuing for some weeks after hatching, NL neurons undergo a complex series of morphological transformations that result in the formation of a steep anteromedial-to-posterolateral gradient of increasing total dendritic length across the nucleus. This gradient perfectly parallels the tonotopic axis of NL. It has been proposed that acoustically evoked activity in the auditory pathway contributes importantly to formation of the gradient of dendritic length in NL and to several other features of dendritic development. The present experiment tested this hypothesis by surgically removing both otocysts (embryonic precursors of the inner ear) and studying the developing NL in the absence of peripheral input. The results of a quantitative study of Golgi-impregnated material show that at E17 both the steepness and predictability of the spatial gradient of dendritic length in operated animals are indistinguishable from normal. Similarly, the correlation of dorsal and ventral dendritic lengths on individual cells in operated animals is not significantly different from normal. The absolute length of both dendritic fields is reduced below normal, although only dorsal dendrites show a statistically reliable (14%) decrease. This is a significantly smaller effect than the 44% length reduction seen previously in animals with unilateral otocyst removal (T.N. Parks: J. Comp. Neurol. 202:47-57, '81); symmetrical afferent input appears more important to the regulation of NL dendritic length than the absolute level of this input.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation of Simonsiella sp. from a neonate

A member of the genus Simonsiella, presumptively identified as S. muelleri, was isolated from a gastric aspirate taken from a neonate 15 min postpartum. The neonate showed a dental cyst and early eruption of teeth, confirmed by mandibular X ray. The morphological features, cultural characteristics, and antimicrobial susceptibility of the isolate are presented.

Location of T-cell leukaemia cells in a model rat system by means of a fluorescent probe

Fluorescence probes for the active centre of an enzyme associated with tumour cells have been used to locate leukaemia cells in a model rat system. These fluorescent techniques are inexpensive and rapid to carry out. The leukaemic cells can be located by fluorescence microscopy in frozen sections, wax embedded sections and resin embedded sections. The technique is illustrated with reference to sections of leukaemic rat kidney, epididymis and testis. These studies confirm earlier histological findings employing conventional staining techniques and have the advantage that individual leukaemia cells can be detected in leukaemic animals undergoing drug therapy. The evidence suggests that these techniques will be of value in further studies of the design of drugs directed to leukaemia cells.

Fluorescent inhibitors of a cell surface protease used to locate leukaemia cells in kidney sections

Guanidinobenzoatase is a trypsin-like protease on the surface of cells capable of migration, for example leukaemia cells. We have used a number of fluorescent probes that are competitive inhibitors of guanidinobenzoatase to locate leukaemia cells in resin sections of kidney tissue obtained from leukaemic rats. We have demonstrated how this competitive inhibition system can be used to direct desired molecules (such as cytotoxic drugs) to these cells and to monitor the arrival of such compounds at the active site of guanidinobenzoatase. The principles developed in this study could equally well be applied to other enzymes on other cells provided suitable competitive inhibitors were designed. The presence of an enzyme on the surface of a cell can be used to direct molecules to that cell provided that these molecules contain a functional group that acts as an inhibitor for the chosen enzyme.