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Biomedical subjects

B M Davis

Publications and source records attributed to B M Davis.

At least 109 records · Page 6Linked to original sources
PubMed1985

Plasma homovanillic acid concentration and the severity of schizophrenic illness.

Concentrations of plasma homovanillic acid before treatment were highly correlated with global severity of illness in schizophrenic patients, both before and after treatment. In contrast, a fixed dose of haloperidol did not affect those concentrations. Thus, in patients with a diagnosis of schizophrenia, plasma homovanillic acid may reflect the severity of illness, but not be influenced by short-term pharmacological perturbations by neuroleptics.

Adult↗
PubMed1985

Evaluating prolactin response to dopamine agonists in schizophrenia. Methodological problems.

Serum prolactin (PRL) level was assessed after challenges with apomorphine hydrochloride, saline, dopamine hydrochloride, or levodopa-carbidopa (Sinemet) in 19 control and 38 chronic schizophrenic subjects. Baseline PRL level varied inversely with age. High correlations existed between baseline PRL level and any subsequent absolute measure of PRL after administration of a dopamine agonist or placebo. Percent decrease was not a function of baseline concentrations and was therefore the only independent measure of drug response. Baseline PRL level was generally lower during exacerbation than remission in patients studied during two states of illness. Percent PRL level decrease after apomorphine administration was significantly greater in normal subjects than in schizophrenics. Correction of apomorphine responses for corresponding placebo (saline) values abolished differences between groups. Prolactin responses after dopamine or levodopa-carbidopa did not differ; however, placebo correction was not possible.

Acute Disease↗
PubMed1985

Apomorphine has no effect on plasma homovanillic acid in schizophrenic patients.

Previous experiments suggest that pharmacological perturbations of the brain dopaminergic system may be reflected by concentrations of plasma homovanillic acid. This study examined the ability of low-dose apomorphine to reduce plasma homovanillic acid concentrations in schizophrenic patients chronically treated with neuroleptics. The data suggest that apomorphine does not reduce plasma homovanillic acid in those patients.

Adult↗
PubMed1985

Clinical studies of the cholinergic deficit in Alzheimer's disease. I. Neurochemical and neuroendocrine studies.

Autopsy studies indicating that cholinergic neurons are selectively lost in patients with Alzheimer's disease (AD) and senile dementia of the Alzheimer type (SDAT) suggest that peripheral markers for central cholinergic activity would be useful in diagnosis. The present studies found that cerebrospinal fluid (CSF) concentrations of acetylcholine (ACh) correlated with the degree of cognitive impairment (r = .70) in a sample of carefully diagnosed patients with AD/SDAT, but metabolites of other neurotransmitters were not related to cognitive state; this suggests that CSF ACh may be a valid measure of cholinergic degeneration. Cortisol and growth hormone were measured in plasma samples drawn from patients and controls every 30 minutes from 2100 to 1100 hours the next day. Mean plasma cortisol concentrations were higher in patients with AD/SDAT than in controls and correlated inversely with CSF methoxy-hydroxyphenylglycol (MHPG) (r = .61) and positively with degree of cognitive impairment (r = +.53); as anticholinergic drugs suppress cortisol this finding indicates that cortisol dysregulation may be a marker for abnormalities in other neurotransmitter systems, particularly the noradrenergic system. Growth hormone secretion was not different in patients and controls but was positively correlated with CSF MHPG (r = +.63).

Acetylcholinesterase↗
PubMed1985

Clinical studies of the cholinergic deficit in Alzheimer's disease. II. Psychopharmacologic studies.

Two studies investigated the ability of physostigmine, given both intravenously and orally, to reduce symptoms of Alzheimer's disease. Intravenous physostigmine significantly and reliably enhanced memory in 13 of 16 patients tested, but the dose producing the improvement varied among patients. Oral physostigmine decreased overall symptom severity in a reliable way in seven of 12 patients tested. The extent of improvement was correlated with the increase in mean cortisol secretion produced by physostigmine, suggesting that the drug improved behavior and cognition only to the extent that it had a specific central cholinomimetic effect. There was no significant association between response to physostigmine and results of a dexamethasone suppression test and physostigmine had no effect on growth hormone secretion.

Administration, Oral↗
PubMed1985

Potentiation of transmission at Ia-motoneuron connections induced by repeated short bursts of afferent activity.

Single medial gastrocnemius Ia-afferent fibers and motoneurons to which they projected were simultaneously impaled in anesthetized cats. Each Ia-afferent fiber was electrically stimulated once every 2 s with short high-frequency bursts (32 shocks at 167 Hz) followed by 1-11 test shocks. The resulting motoneuron excitatory postsynaptic potentials (EPSPs) were recorded and averaged in register. The interval between the end of one burst and the beginning of the next was 2 s; therefore, the amplitude of the first EPSP in the burst was considered to be a measure of efficacy of transmission 2 s after the burst. At most connections (23/29) the mean amplitude of the first EPSP in the burst was equal to or larger than the mean amplitude of control EPSPs produced by low-frequency (18-Hz) stimulation. Enhancement of transmission was maximum 50-100 ms after the burst, and the amplitude of the test EPSP delivered at this time was always greater than that of the control. The period of enhanced transmission appeared to decay more rapidly at connections with small EPSPs. The greatest amount of EPSP amplitude enhancement at 50 or 100 ms after the burst was observed at connections at which EPSP amplitude increased during the burst. The shape (rise time, half width) of potentiated EPSPs was the same as control EPSPs averaged during low-frequency (18-Hz) stimulation. Multiple shocks delivered at low frequency between bursts revealed that enhanced transmission following the high-frequency burst is very sensitive to the effects of low-frequency test stimulation. Furthermore, increasing the number of shocks during the interval between bursts reduced the enhancement of the first EPSP in the burst. We suggest that modulation of synaptic transmission after high-frequency bursts differs across Ia-motoneuron connections. These time-dependent changes associated with short bursts of firing (which are similar in frequency to those observed in Ia-fibers supplying hind-limb muscles during stepping) emphasize the necessity to consider the history of the discharge pattern of the group Ia fiber in assessing efficacy at individual Ia-motoneuron connections.

Animals↗
PubMed1985

Oral physostigmine treatment of patients with Alzheimer's disease.

Twelve patients with Alzheimer's disease received 0.0, 0.5, 1.0, 1.5, and 2.0 mg of oral physostigmine every 2 hours for 3-5 days; symptoms after each dose were assessed with the Alzheimer's Disease Assessment Scale. Placebo and the dose associated with the least severe symptoms were then readministered for 3-5 days each. Of the 10 patients who completed the study, three showed clinically significant improvement on the highest physostigmine dose in both phases, four more were marginally improved in both phases, and three had inconsistent responses to physostigmine. Cortisol measures obtained during a sleep study suggest that patients whose symptoms improved on physostigmine were those in whom oral physostigmine enhanced central cholinergic activity.

Administration, Oral↗
PubMed1984

The distribution of enkephalinlike immunoreactivity in the telencephalon of the adult and developing domestic chicken.

Immunohistochemical techniques were used to determine the distribution of enkephalinlike immunoreactivity in the telencephalon of chicken. The densest accumulation of enkephalinergic neurons and fibers was observed within the paleostriatal complex, the avian equivalent of the mammalian basal ganglia. Numerous small enkephalinergic neurons were observed in both lobus parolfactorius (LPO) and the paleostriatum augmentatum (PA), the two components of the small-celled portion of the paleostriatal complex. The enkephalinergic neurons of LPO-PA appeared to give rise to a dense plexus of enkephalinergic fibers within the large-celled zone of the paleostriatal complex, the paleostriatum primitivum (PP). The distribution of enkephalin within the avian paleostriatal complex, when compared to the distribution of enkephalin within the mammalian basal ganglia, supports previous proposals that PP is comparable to the mammalian globus pallidus and that PA-LPO are comparable to the caudate-putamen (Karten and Dubbeldam, '73; Kitt and Brauth, '81; Parent and Olivier, '70; Reiner et al., '83). Observations on the development of enkephalinlike immunoreactivity within the chicken paleostriatal complex also support the suggestion that the major component nuclei of the avian paleostriatal complex have correspondents within the mammalian basal ganglia. Enkephalinlike immunoreactivity was also observed within cell bodies and fibers in other portions of the avian telencephalon. Within the ventrolateral telencephalon, the nucleus accumbens, nucleus of the diagonal band, and tuberculum olfactorium contained enkephalinergic cell bodies and fibers while only enkephalinergic fibers were observed in the portion of the avian telencephalon that has been termed the ventral paleostriatum (Kitt and Brauth, '81; Reiner et al., '83). Within the medial wall of the telencephalon, enkephalinergic fibers were observed in the lateral septal nucleus, while enkephalinergic cell bodies and fibers were observed in the parahippocampal area. Little enkephalinlike immunoreactivity was observed dorsal to the paleostriatal complex except in the hyperstriatum dorsale. Within the hyperstriatum dorsale, a band of enkephalinergic neurons appeared to give rise to an overlying parallel band of dense enkephalinergic fibers. The distribution of enkephalinlike immunoreactivity within the avian telencephalon thus shows remarkable similarity to that seen in the mammalian telencephalon. The largest accumulation of enkephalinlike immunoreactivity within the telencephalon of both vertebrate classes appears to be found within the ventrolateral wall of the telencephalon, including the basal ganglia.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Apomorphine and schizophrenia. Treatment, CSF, and neuroendocrine responses.

Previous studies have variably reported the efficacy of apomorphine in treatment of schizophrenia and tardive dyskinesia. Stimulation of dopamine neuron autoreceptors is the presumed mode of action. Low-dose apomorphine (0.75 mg subcutaneously) and placebo were administered to 25 male schizophrenics to evaluate the drug's effect on psychotic and tardive dyskinetic symptoms. No significant improvement or deterioration was seen. Concomitant measurements of plasma prolactin and growth hormone levels and CSF homovanillic acid level indicated that the dose used was centrally active. These results indicate that an active though nonsedating dose of apomorphine does not ameliorate symptoms of schizophrenia or tardive dyskinesia.

Adult↗
PubMed1984

Effects of spinal lesions on substance P levels in the rat sympathetic preganglionic cell column: evidence for local spinal regulation.

Substance P has been localized to the neuropil of sympathetic preganglionic neurons in light and electron microscopic studies. Two recent reports have suggested that the majority of substance P in the rat intermediolateral cell column was contained in synaptic terminals of bulbospinal axons. However, previous investigations in our laboratory indicated the presence of major substance P spinal-sympathetic preganglionic neuron circuitry in pigeon. The present study used radioimmunoassay and immunohistochemistry to examine substance P levels in rat intermediolateral cell column following various spinal lesions in order to assess the relative contributions of bulbospinal and intraspinal substance P neurons to the substance P content of the intermediolateral cell column. The results from these experiments support the existence of both bulbospinal and intraspinal substance P-containing projections to the rat intermediolateral cell column. In addition, characterization of spinal cord substance P-like immunoreactivity by combined high performance liquid chromatography and radioimmunoassay, revealed that substance P in rat intermediolateral cell column was indistinguishable from synthetic substance P. Following transection of thoracic spinal cord, substance P-immunoreactive staining was still evident in the intermediolateral cell column caudal to the lesion. These substance P-positive fibers were studded with bouton-like swellings and appeared normal. Following high cervical hemisection, depletion of substance P (radioimmunoassay measurements) was bilateral and equal in the intermediolateral cell column: 25% depletion was observed after 7 days and 35% depletion after 14 days. However, rats which were hemisected at low cervical and/or mid-thoracic levels contained normal or elevated amounts of substance P in the intermediolateral cell column. Since substance P remains in the intermediolateral cell column following total transection, substance P spinal-sympathetic preganglionic neuron circuitry must exist. Additionally, depletion of substance P following high cervical hemisection suggests the existence of a substance P-containing, bilateral bulbospinal pathway to the intermediolateral cell column. The observation that substance P levels were normal or elevated following low cervical lesions raises the possibility that intraspinal substance P neurons can compensate for loss of substance P in the spinal cord. Sprouting or altered substance P metabolism and/or release by intraspinal substance P neurons could be responsible, suggesting an important homeostatic mechanism for maintaining substance P content within the intermediolateral cell column.

Animals↗
PubMed1984

Prognostic significance of subepidermal immune deposits in uninvolved skin of patients with systemic lupus erythematosus: a 10-year longitudinal study.

The detection by direct immunofluorescence of subepidermal immune deposits in clinically normal skin of patients with systemic lupus erythematosus has become known as a positive lupus band test (LBT). To gain a better understanding of the relation between the LBT and prognosis in systemic lupus erythematosus (SLE) a prospective longitudinal study has been carried out in 51 SLE patients covering a 10-year period. A total of 223 LBTs were obtained from clinically normal skin of the medial volar forearm on these 51 patients (average, 4.4 per patient) and the results correlated with clinico-pathologic features of the disease and outcome. Findings from the initial LBT (obtained while on no systemic therapy) were used to divide patients into LBT-positive and LBT-negative groups. With the exception of patients subsequently treated with daily doses of prednisone greater than 40 mg or cytotoxic agents, the patients in the LBT-positive group usually remained LBT-positive. The LBT-negative patients usually remained LBT-negative on repeated testing. A comparison of clinical features in the two groups revealed a 55% prevalence of lupus nephropathy in the LBT-positive group as opposed to 23% in the LBT-negative group (p = 0.025). Although the two groups had similar serum creatinine levels at the time of the initial LBT, the maximum serum creatinine (mean, 3.0 mg/dl) in the LBT-positive group was significantly higher than the maximum (mean, 1.2 mg/dl) in the LBT-negative group (p = 0.04). Furthermore, only 9% of renal biopsies in the LBT-negative group showed diffuse proliferative glomerulonephritis in contrast to 65% of biopsies in the LBT-positive group (p = 0.007). Lastly, the two groups were compared with regard to outcome; 10-year survival from the time of diagnosis was 95% in the LBT-negative group as opposed to only 54% in the LBT-positive group (p = 0.007). These findings indicate that a positive LBT has predictive value in that it identifies a subset of SLE patients with more aggressive renal disease and significantly decreased long-term survival.

Adolescent↗
PubMed1984

Age and the dexamethasone suppression test in depression.

The authors examined the effects of age on plasma cortisol concentrations of 81 depressed men after dexamethasone administration. Dexamethasone nonsuppression was significantly more frequent in patients older than age 55 than those younger. Similarly, older patients had significantly higher postdexamethasone cortisol concentrations than younger patients at all time points sampled. These differences could not be attributed to severity or to the prevalence of psychosis in older and younger depressed patients.

Adolescent↗
PubMed1984

Substance P-containing pathways to avian sympathetic preganglionic neurons: evidence for major spinal-spinal circuitry.

The origin of substance P-like immunoreactivity (SPLI) in the neuropil of sympathetic preganglionic neurons (SPNs) was investigated in pigeon (Columba livia). Previous investigators had suggested that a major SPLI-containing projection to SPNs arose from caudal brainstem (Johansson, O., T. Hokfelt, B. Pernow, S. L. Jeffcoate, N. White, H. W. M. Steinbusch, A. A. J. Verhofstad, P. C. Emson, and E. Spindel (1981) Neuroscience 6: 1857-1881; Gilbert, R. F. T., P.C. Emson, S. P. Hunt, G. W. Bennett, C. A. Marsden, B. E. B. Sandberg, H. W. M. Steinbusch, and A. A. J. Verhofstad (1982) Neuroscience 7: 69-87; Helke, C. J. J. J. Neil, V. J. Massari, and A. D. Loewy (1982) Brain Res. 243: 147-152) and, furthermore, that the bulbospinal fibers and terminals in the SPN neuropil which contained SPLI also contained serotonin-like immunoreactivity (5-HTLI) (Johansson, O., T. Hokfelt, B. Pernow, S. L. Jeffcoate, N. White, H. W. M. Steinbusch, A. A. J. Verhofstad, P. C. Emson, and E. Spindel (1981) Neuroscience 6: 1857-1881; Gilbert, R. F. T., P.C. Emson, S. P. Hunt, G. W. Bennett, C.A. Marsden, B. E. B. Sandberg, H. W. M. Steinbusch, and A. A. J. Verhofstad (1982) Neuroscience 7: 69-87). In the present study, various spinal lesions were made and the SPLI and 5-HTLI content of thoracic spinal cord was examined using immunohistochemistry. Interruption of descending bulbospinal fibers by cervical hemisection had no demonstrable effect on SPLI in the SPN neuropil, while 5-HTLI was almost totally depleted in the half of the spinal gray (including the SPN cell column) ipsilateral to the hemisection. Following a complete thoracic transection, SPLI was only depleted 2 to 3 mm rostral and caudal to the lesion, while normal SPLI staining was present in the remainder of the spinal cord. 5-HTLI was totally depleted caudal to a thoracic transection. Dorsal rhizotomy of three to six sequential spinal segments significantly depleted SPLI in the dorsal horn but had no effect on SPLI in the region of SPNs. Major depletion of SPLI within the SPN cell column was only seen when portions of thoracic spinal cord were isolated by complete transections or unilateral hemisections. Finally, evidence was found for intraspinal SPLI-containing fiber systems. These results demonstrate that the majority of SPLI in the SPN cell column in the pigeon is probably of intraspinal origin. The data also confirm that 5-HTLI is contained in axons and terminals arising from cell bodies of supraspinal origin.

Animals↗
PubMed1983

Gamma-hydroxybutyrate in the treatment of schizophrenia.

Gamma-Hydroxybutyrate (GHB) inhibits firing of dopaminergic neurons and is thus potentially useful in the treatment of schizophrenia. GHB was administered to 10 schizophrenics concurrently with low-dose fluphenazine in a 6-week double-blind crossover study. No antipsychotic efficacy of GHB was noted. GHB had little if any effect on plasma prolactin levels after a single administration and caused few side effects. Trials with higher doses of GHB may be warranted.

Adult↗
PubMed1983

DST in depression is unaffected by altering the clock time of its administration.

Circadian oscillators in major depressive illness may be phase advanced by several hours. We attempted to determine whether phase advance of the oscillator responsible for hypothalamic-pituitary-adrenal (HPA) function in depressives might influence the outcome of the overnight dexamethasone suppression test (DST). Six major depressives underwent DST with dexamethasone doses administered in a randomized fashion at 1900h and 2300h on separate evenings. Twenty-four hour cortisol secretory patterns basally and postdexamethasone were obtained for each subject. Postdexamethasone cortisol responses were similar for both the 1900h and 2300h dosage schedules in suppressors, nonsuppressors, and an early escape responder. We conclude that failure of the HPA axis to suppress normally with DST in major-depressive illness is a primary feature of neuroendocrine regulatory mechanisms rather than secondary to a posited phase advance of the related circadian oscillator.

Aged↗
PubMed1983

Effects of propantheline bromide on basal growth hormone, cortisol and prolactin levels.

Propantheline bromide, a peripheral anticholinergic drug with muscarinic and nicotinic blocking properties, was given by mouth to normal young men. Propantheline (45 mg) significantly lowered basal growth hormone concentrations at 0800 hr, 12 hr after administration. Propantheline (30 mg) tended (p = 0.08) to lower growth hormone concentrations at 1200 hr, 16 hr after administration. Cortisol and prolactin levels were not changed 12, 16 and 20 hr after propantheline (30 mg) nor 12 hr after propantheline (45 mg).

Adult↗