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.

Charge transfer-oxy radical mechanism for anti-cancer agents

The proposal is advanced that anti-cancer drugs generally function by charge transfer resulting in formation of toxic oxy radicals which destroy the neoplasm. Electrochemical studies were performed with some of the main types of agents: iminium ions (adenine iminium from alkylating species, iminium metabolite of 6-mercaptopurine, nitidine, other polynuclear iminiums) and metal complexes (Pt(II)diaquodiammine-guanosine, copper salicylaldoximes). Reduction potentials ranged from -0.4 to -1.2 V. Literature data for quinones are presented and radiation is discussed. Based on the theoretical framework, a rationale is offered for the carcinogen-anti-cancer paradox and the role of antioxidants.

Prepubertal growth and skeletal maturation in children with sickle cell disease

In a longitudinal study of 298 children with homozygous sickle cell (SS) disease and 157 children with hemoglobin SC disease, between birth and 9 years of age, observations of weight and height were made. These were compared with similar data derived from an age- and sex-matched group of 231 children with a normal hemoglobin (AA) genotype. Growth in children with SC disease was not significantly different from that in normal children, but children with SS disease had statistically significant, and progressive, deficits in both weight and height before 2 years of age. The average deficit approached 1 SD below the normal mean for age by 9 years. Observations of skeletal maturity, based on radiologic assessment of bone age at the wrist, were made on a proportion of these children at 5 and 8 years of age. Children with SS disease were significantly retarded at 8 years but not 5 years, which is consistent with increasing deficit in height. These observations confirm the early impact of SS disease on physical development and provide standards from which clinical expectations of growth may be derived. The relevance of these findings and their relationship to the characteristic delay in pubertal development is discussed together with a review of possible etiologic factors. The benign nature of SC disease is endorsed by the absence of an effect on growth in the prepubertal child.

Study using in-vivo binding of 125I-labelled hCG, light and electron microscopy of the repopulation of rat Leydig cells after destruction due to administration of ethylene-1,2-dimethanesulphonate

Gonadotrophin binding to rat Leydig cells after a single administration of ethylene dimethanesulphonate (EDS) (75 mg/kg i.p.) was followed by using intratesticular microdoses of 125I-labelled hCG, whilst corresponding morphological changes in the testicular interstitium were studied with light and electron microscopy. No discernible effect on 125I-labelled hCG binding compared with controls was observed until 24 h after treatment. Between 24 and 32 h a sharp decline in binding occurred which was correlated with extensive Leydig cell destruction. By 48 h the 125I-labelled hCG binding was negligible and no morphologically recognizable Leydig cells were found at this time. The specific binding remained low until 21 days after treatment and then a marked increase occurred to give nearly normal levels by 49 days. This was consistent with a generalized repopulation of the interstitium with Leydig cells, seemingly the result of differentiation of fibroblast-like precursor cells.

Evidence for the involvement of kainate receptors in synaptic transmission in the avian cochlear nucleus

Previous studies using various excitatory amino acid antagonists have shown that synaptic transmission between the auditory nerve and the cochlear nucleus of chickens (nuc. magnocellularis; NM) is mediated by non-N-methyl-D-aspartate (non-NMDA) receptors. In the present study we have attempted to define the subclass of non-NMDA receptor in the NM by examining the effects of various excitatory amino acid agonists on synaptically evoked field potentials in an in vitro preparation of the chicken brain stem. Both quisqualate and DL-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), whose actions operationally define the quisqualate receptor class, caused variable and weak depression of evoked responses in the NM, as did L-glutamate. Kainic acid, on the other hand, completely blocked postsynaptic responses at micromolar concentrations. We conclude that kainate-preferring non-NMDA receptors play a predominant role in mediating transmission in the NM.

Non-N-methyl-D-aspartate receptors mediating synaptic transmission in the avian cochlear nucleus: effects of kynurenic acid, dipicolinic acid and streptomycin

We have examined the effects of a number of excitatory amino acid antagonists on transmission at the cochlear nerve-nucleus magnocellularis synapse in the chicken. Using an in vitro preparation and bath application of drugs, we studied the effects of kynurenic acid and several related substances, streptomycin and a selective N-methyl-D-aspartate receptor antagonist, DL-alpha-aminosuberate. The last compound had no effect on evoked transmission. Of the various kynurenic acid-related compounds tested, only kynurenic and dipicolinic acid selectively altered responses in nucleus magnocellularis. Quinolinic acid, a kynurenic acid analogue that is structurally akin to dipicolinic acid but which acts selectively at N-methyl-D-aspartate receptors, was without effect. The effect of kynurenic acid was solely inhibitory, completely blocking postsynaptic responses with a potency dependent on the frequency of nerve stimulation. No such frequency dependence was seen with dipicolinic acid although this compound also completely suppressed evoked responses. In addition dipicolinic acid potentiated postsynaptic responses at concentrations only slightly lower than those causing inhibition. Streptomycin inhibited responses in nucleus magnocellularis but this effect seems to result partially from the ability of the drug to inhibit presynaptic calcium influx. Our finding that selective antagonists of N-methyl-D-aspartate receptors were ineffective while antagonists of both receptor types, such as kynurenic and dipicolinic acids, inhibited evoked responses reinforces the conclusion that postsynaptic receptors mediating transmission at this synapse are of the non-N-methyl-D-aspartate type [Nemeth et al. (1983) Neurosci. Lett. 40, 39-44].(ABSTRACT TRUNCATED AT 250 WORDS)

CT diagnosis of fluid in lesser sac mimicking thrombosis of inferior vena cava

A patient with ascites and fluid in the lesser sac mimicking the appearance of a clot in the inferior vena cava is described. A knowledge of liver anatomy, particularly the lesser sac in the region of porta hepatis, aids in avoiding this CT pitfall.