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Biomedical subjects

H H Holcomb

Publications and source records attributed to H H Holcomb.

45 records · Page 3Linked to original sources
PubMed1983

Effects of electroconvulsive therapy on mood, parkinsonism, and tardive dyskinesia in a depressed patient: ECT and dopamine systems.

A patient suffering from delusional depression, Parkinson's disease, and tardive dyskinesia (TD) exhibited a marked improvement in mood and parkinsonian symptoms following electroconvulsive therapy (ECT). In contrast, her TD symptoms worsened. The inverse relation between the intensity of TD symptoms on the one hand and the parkinsonian and depressive symptoms on the other is discussed with respect to ECT's effect on central dopaminergic systems.

Aged↗
PubMed1982

Striatal dopamine autoreceptors uninfluenced by chronic administration of antidepressants.

Dopamine (DA) receptor sensitivity to apomorphine (APO) was assessed in the rat nigrostriatal system following chronic antidepressant treatment. Imipramine (IMI), iprindole (IPR) or vehicle was administered to rats for 10 days (10 mg/kg i.p., b.i.d.). Two and a half days after the last injection 3,4-dihydroxyphenylacetic acid (DOPAC) levels were measured in rat striata following injection of APO (50 or 100 micrograms/kg s.c.) or vehicle. In contrast with rats receiving chronic vehicle injections, rats chronically treated with IMI or IPR failed to exhibit a significant APO-induced fall in striatal DOPAC levels. Antidepressant-treated animals, however, exhibited significantly lower basal DOPAC levels than vehicle-treated rats. In an effort to localize the diminished APO response, DA autoreceptor sensitivity to APO was assessed in drug- and vehicle-treated animals. Employing gamma-butyrolactone (GBL) and a dihydroxyphenylalanine (DOPA) decarboxylase inhibitor to elevate striatal DOPA, the APO-induced reversal of DOPA elevation was used as an index of DA autoreceptor sensitivity. This GBL-stimulated in vivo tyrosine hydroxylation was similarly reversed by APO (125, 250 or 500 micrograms/kg i.p.) in IMI-, IPR- and vehicle-treated animals. In view of these findings, we propose that the blunted biochemical response to APO observed in animals pretreated with antidepressants does not originate as a result of alterations in the sensitivity of DA autoreceptors located on the striatal presynaptic nerve terminal.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1982

Effect of chlorpromazine on H-reflex recovery curves in normal subjects and schizophrenic patients.

This study sought to determine the effect of chlorpromazine (CPZ) on a physiological measure, the H-reflex recovery curve (HRRC) and to determine whether the effect is different in normal subjects and schizophrenic patients. Eleven normal control subjects and 14 patients were administered 12.5 and 25.0 mg CPZ by IM injection. On the average. HRRCs measured 90 min after the injections were lower compared to pre-injection levels in both groups, at both doses. In general, the higher dose was more effective in both groups. Half of the patients, however, failed to respond to 12.5 mg, indicating that some schizophrenics are less sensitive than normals to CPZ. These results indicate that excessive dopamine activity or sensitivity may underlie abnormally high HRRCs in unmedicated psychotic patients.

Adolescent↗
PubMed1977

Selective attention and eye movements while viewing reversible figures.

This study suggests that different eye-movement patterns are associated with reversals of ambiguous figures. The high scanners seem to be more dependent on eye movements for reversals and their recognition of each pattern depends on the sequence and location of fixations; thus shifts of attention appear to be externalized in the form of large, saccadic eye movements. In contrast low scanners are better able to shift attention internally, e.g., by mental restructuring, without large eye movements. We further suggest that scanning behavior associated with reversals may be modulated by stimulus complexity, figures' reversibility, and extrinsic/intrinsic motivational styles.

Adult↗
PubMed1976

Prolactin binding in rat mammary gland during pregnancy and lactation.

Lactogenic hormones from the placenta and pituitary are primarily responsible for the growth and function of the mammary gland during pregnancy and lactation. In the present study we described the optimal conditions for the measurement of 125I-labeled ovine prolactin binding to mammary gland slices of pregnant and lactating rats. Prolactin binding is saturable (Kd approx. 2.36 - 10(-9) M), hormone specific and destroyed by proteases. The hormonal environments of pregnancy and lactation dramatically influence the availability and measurement of prolactin binding sites. Whereas binding consistently appears to be low in mammary glands removed from rats during pregnancy, binding levels rise 7--8-fold shortly after birth and remain high during the 22 days of lactation. However, the removal of the ovaries and gravid uteri at specific times during pregnancy results in a prompt 3--6-fold increase in prolactin binding. Elevated levels in potential prolactin binding capacity appear in mammary tissue coincident with the reported rise in serum rat placental lactogen between the eighth and eleventh days. We suggest that high levels of this lactogenic hormone promote the appearance of prolactin binding sites during pregnancy and mask the sites such that they are not available for measurement in vitro.

Animals↗
PubMedDate not supplied

Anatomical localization for PET using MR imaging.

Accurate localization of an imaging plane of interest is often needed prior to a positron emission tomographic (PET) study. We have developed a simple method for accurate and reproducible selection of an imaging plane for PET using magnetic resonance (MR) imaging. This method is useful when optimal sampling of specific brain structures, such as small subcortical nuclei, or when a specific imaging angle is required for the PET study. An external localizing device, consisting of a series of tubes visible on MR, is affixed to an individually fitted thermoplastic mask. This mask system is worn by the patient during both the MR and PET studies. A plane of interest is planned from the sagittal MR image and defined by its relation to the localizing device and to the MR scanner's "landmark" or reference position. This plane is transferred to the mask by means of a calibrated alignment laser. The coplanar acquisition of MR and PET images allows individualized analysis of brain structure-function relationships. Phantom studies demonstrated the accuracy and reproducibility of imaging plane selection by this method to be within 1 mm and 1 degree. Application of the localization protocol in a human subject is also presented.

Adult↗
PubMedDate not supplied

PET-FDG test-retest reliability during a visual discrimination task in schizophrenia.

OBJECTIVE: Reliability of assessment is important in any kind of neuropsychiatric study, but is particularly pivotal in schizophrenia research where symptom instability is common. MATERIALS AND METHODS: Two fluorodeoxyglucose PET scans, 1 week apart, were carried out in schizophrenic patients while they were performing a simple visual discrimination task. Subject and scan conditions were held constant. Regional metabolic rates of glucose utilization were calculated as absolute and scaled; they were compared using correlational statistics. RESULTS: Average differences between scans were 5-9% for the parietal and occipital cortices, but 1-3% for other cortical areas, differences comparable with reported variances in normal controls. CONCLUSION: These results suggest that test-retest variance in metabolic imaging in schizophrenia is relatively low and that task performance increases metabolic stability in brain areas unrelated to task performance.

Adult↗
PubMedDate not supplied

Insulin-resistant diabetes with insulin receptor autoantibodies in a male patient without acanghosis nigricans.

A 51-yr-old, nonobese, male patient presented with hyperglycemia and a recent 40-pound weight loss. Severe insulin resistance was documented in studies in which high amounts of insulin were infused using the Biostator GCIIS. Diabetic control was finally achieved with subcutaneous injections of 470 U of insulin per day. Positive laboratory findings included a mild pancytopenia, elevated erythrocyte sedimentation rate, decreased C3 and properdin, and increased IgA. Antinuclear or other autoantibodies were not present. Insulin antibody levels were within the range usually present in insulin-treated diabetic patients. Acanthosis nigricans was not present. Incubation of the patient's serum with IM-9 lymphoblastoid cells revealed that an insulin receptor antibody was present in a serum dilution of 1:80. Insulin-resistant diabetes mediated by insulin receptor antibodies may present in patients with immunologic findings but without overt dermatologic stigmata.

Acanthosis Nigricans↗