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Biomedical subjects

P H Smith

Publications and source records attributed to P H Smith.

At least 19 recordsLinked to original sources
PubMed1992

Genetics of the hemolymph esterases of Lucilia cuprina (Diptera: Calliphoridae).

When hemolymph from adults of Lucilia cuprina was partitioned on native polyacrylamide gels, nonspecific esterase staining demonstrated 10 bands with up to six bands in an individual. The bands derive from alleles at two loci, EHA (five alleles) and EHB (four alleles). EHA is located on chromosome 4, 16.3 map units from sv (singed vibrissae) and 22.1 map units from ra (radial vein gaps). EHB is located on chromosome 5, 34.0 map units from to2 (topaz2 eyes) and 7.2 map units from mv (M1-veinless).

Animals↗
PubMed1992

Concomitance of psoriasis and atopic dermatitis.

There is a widespread belief that psoriasis (Ps) and atopic dermatitis (AD) are clinically mutually exclusive. A prospective study was undertaken to record the concurrent and/or consecutive coincidence of the two conditions and any shared clinical features. Patients attending a dermatology clinic were systematically examined for the presence of Ps and/or AD. Nine hundred and eighty-three patients were studied--428 with Ps, 224 with AD, 45 with both Ps and AD, and 286 controls. Of AD patients 16.7% had Ps, and 9.5% of Ps patients had AD. In consecutive occurrences, Ps generally followed AD. The ratio of concurrent to consecutive incidences was 3:1. The two diseases are shown not to be mutually exclusive and may coexist in the same individual.

Adolescent↗
PubMed1992

Intracellular recordings from neurobiotin-labeled cells in brain slices of the rat medial nucleus of the trapezoid body.

Principal cells in the medial nucleus of the trapezoid body (MNTB) are believed to be critical components in the circuit subserving sound localization. These cells, located in the superior olivary complex, convert excitatory inputs, arriving from the contralateral cochlear nucleus by way of large somatic synapses (the calyces of Held), to inhibitory projections onto principal cells in the ipsilateral lateral superior olive (LSO). We have characterized a population of cells in the rat MNTB using intracellular recording and labeling techniques in a brain slice preparation. MNTB principal cells had spherical or ellipsoid somata that gave rise to single large-diameter dendrites, which branched extensively and often extended beyond the borders of MNTB. Commonly observed axonal projection targets included LSO, the superior paraolivary nucleus, and the medial superior olive, and occasionally the lateral nucleus of the trapezoid body. The projections of individual MNTB cells showed an orderly topography that is consistent with the known tonotopic maps of the nuclei. In response to current injection, principal cells exhibited several nonlinearities, including rectification for depolarizing currents and a "sag" in the membrane potential for hyperpolarizing currents. Superthreshold depolarizing currents elicited transient firing behavior. Application of the potassium channel blocker 4-aminopyridine reduced or eliminated the rectification in the current-voltage relationships and caused depolarizing currents to elicit repetitive firing. Stimulation of afferent inputs elicited short-latency spikes, presumably driven by calyceal synaptic inputs; long-latency, presumably polysynaptic, EPSPs; and short- and long-latency IPSPs. The duration of synaptic events was strongly dependent on membrane potential, and this effect was probably due to the intrinsic membrane properties of the cell. In all cases tested, EPSPs were blocked by CNQX or DNQX, and IPSPs were blocked by strychnine. Two injected non-principal cells differed from principal cells in their morphologies and physiological characteristics.

4-Aminopyridine↗
PubMed1992

Anatomy and physiology of multipolar cells in the rat inferior collicular cortex using the in vitro brain slice technique.

Coronal brain slices from 21-50-d-old hooded rats were used to characterize intracellular responses of cells in both the external and dorsal cortices of the inferior colliculus (IC). These cells could generate both sodium and calcium spikes. Depending on current amplitude, depolarizing current pulses could elicit either phasic or tonic firing patterns, with spike frequency adaptation. Spiking also occurred at the offset of a hyperpolarizing pulse. These patterns were due primarily to the activation of calcium conductances. Stimulation of the commissural pathway connecting the left and right IC produced a short-latency monosynaptic IPSP followed by an EPSP(s) and a late polysynaptic IPSP(s). Non-NMDA glutamate antagonists eliminated or reduced the amplitude of the EPSP and the late portion of the inhibition, while both IPSPs were blocked by GABAA antagonists. As described previously in guinea pig (Smith, 1986) and rat (Pierson et al., 1989), a large NMDA-mediated depolarizing event (paroxysmal depolarizing shift, or PDS) could be elicited by shocking the commissure of the IC in the presence of picrotoxin or bicuculline, NMDA, 4-aminopyridine, or in 0 Mg2+ Ringer's. The picrotoxin-induced PDS was significantly reduced or abolished in Ringer's containing aminophosphonovalerate. Cells displaying the responses described were labeled with neurobiotin. Those labeled are medium-sized multipolar cells. Their dendrites are usually spiny and can extend superficially up to the cortical surface. Their thin axons give rise to collaterals that branch profusely within the cortex. The main axons project laterally along the circumference of the IC or medially into the commissure separating the collicular hemispheres.

Animals↗
PubMed1991

Projections of physiologically characterized globular bushy cell axons from the cochlear nucleus of the cat.

We made intraaxonal recordings from 30 individual globular bushy cell axons in the trapezoid body of the cat using HRP-filled glass microelectrodes. With subsequent HRP injection, we determined their axonal projection patterns. For cells with characteristic frequencies (CFs) above 3 kHz, short-tone peristimulus time histograms (PSTHs) at CF were typically primarylike at low tone intensities and primarylike with notch (PLN) or onset with low sustained activity (OL) at higher stimulus levels. Cells with CFs between 1 and 3 kHz showed the same response features with the spikes in the sustained region of the response phase-locked to the stimulus tone. Cells with CFs below 1 kHz showed phase-locked PSTHs with exceptionally high levels of synchrony compared to eighth nerve fibers with comparable CFs. This exceptional phase-locking was also noted when cells with CFs of 1-3 kHz were presented with tones below 1 kHz. Although the globular bushy cell axons were not completely filled from the soma of origin to terminal fields in the contralateral brainstem, a number of consistent anatomical features were distinguished in the population. All but one of the myelinated axons crossed the midline in the middle, large fiber component of the trapezoid body. Ipsilaterally, the axon always gave off from one to four collateral branches whose major targets were the posterior periolivary nucleus (PPO) and the lateral nucleus of the trapezoid body (LNTB). Minor termination sites for ipsilateral collateral branches were the dorsolateral periolivary nucleus (DLPO) and the lateral superior olive (LSO). Contralaterally the axon gave rise to one or two calyces of Held in the medial nucleus of the trapezoid body (MNTB). Three other major collateral branches arose from the contralateral axon and innervated a consistent set of areas. One headed caudally to innervate an area just ventromedial to the facial nucleus. Another followed the sixth nerve dorsally to innervate the dorsomedial periolivary nucleus (DMPO). A third collateral headed rostrally toward the ventral nucleus of the lateral lemniscus (VNLL), giving off occasional small sidebranches. Although each injected axon gave rise to a collateral that innervated the MNTB, it did not necessarily give rise to all three of the other collateral branches.

Action Potentials↗
PubMed1991

Magnetic resonance imaging study of the rat cerebral ventricular system utilizing intracerebrally administered contrast agents.

Magnetic resonance imaging (MRI) was employed to study the rat brain in conjunction with intracerebral (ic) injection of three contrast agents: GdHAM, GdDPTA, and MnCl2. The results demonstrate several advantages of ic administration of MRI contrast agents over the other routes of injection in examining CSF dynamics and brain ventricular structure. Apparent affinity of the luminal ventricular wall of the brain for positively charged GdHAM and Mn2+ ions is observed, presumably reflecting the presence of negatively charged wall components. Respiratory distress caused by (intravenous) injection of GdHAM was found to be minimized in the case of ic injections. Time-dependent changes in observed contrast indicate that diffusive processes rather than flow of CSF play a dominant role in distributing the contrast agents. Possible applications of this approach in brain research are discussed.

Animals↗
PubMed1991

Transsexualism.

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Follow-Up Studies↗
PubMed1990

Some limitations of the radioisotope bone scan in patients with metastatic prostatic cancer. A subanalysis of EORTC trial 30853. The EORTC Urological Group.

This article reviews the serial bone scans of 149 of 327 patients entered into a randomized prospective trial comparing orchidectomy versus zoladex and flutamide in patients with metastatic prostatic cancer. Attention is drawn to the difficulty of evaluating the response rate and of the importance of tumor load in determining survival. The use of sequential bone scans once the diagnosis of metastatic disease has been confirmed is of questionable value as the scans are expensive and contribute little to the further management of the patient in the absence of symptoms requiring relief.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Prostatic specific antigen and the prediction of prognosis in metastatic prostatic cancer.

Serum prostate-specific antigen (PSA) levels were studied in the EORTC trial of zoladex plus flutamide versus orchidectomy in metastatic prostatic cancer. Forty-four of 60 patients had a decrease of PSA to less than or equal to 10 ng/ml at 3 to 6 months after treatment. The combination of a PSA less than 10 ng/ml after 3 to 6 months treatment and less than 15 spots on the bone scintigram at entry gave the highest probability of not having progressed by 24 months. A rising PSA anticipated bone progression by 6 to 12 months in 13 of 28 patients (46%). The PSA at entry to the trial was related to survival; a discriminant of 300 ng/ml distinguished a poor and better risk group. The lowest level of PSA reached during the first 6 months of treatment was also a univariate survival factor.

Antigens, Neoplasm↗
PubMed1990

Orchidectomy vs. Zoladex plus flutamide in patients with metastatic prostate cancer. The EORTC GU Group.

Treatment with bilateral orchidectomy was compared with Zoladex, 3.6 mg depot, plus flutamide, 250 mg t.i.d., in a randomized prospective study by the European Organization for Research and Treatment of Cancer (EORTC). Small but statistically significant differences in time to subjective and objective progression of disease were found in favor of Zoladex plus flutamide. However, time from objective progression to death was longer in the orchidectomy group. The clinical significance of these differences requires further follow-up and analysis. No difference was found in overall survival between the 2 treatment groups.

Aged↗