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Biomedical subjects

L Holt

Publications and source records attributed to L Holt.

At least 37 records · Page 2Linked to original sources
PubMed1995

Antinuclear antibodies in early onset pauciarticular juvenile chronic arthritis (JCA) are associated with HLA-DQB1*0603: a possible JCA-associated human leucocyte antigen haplotype.

A panel of 43 early onset pauciarticular (EOPA) juvenile chronic arthritis (JCA) patients have been typed for human leucocyte antigens (HLA) DRB1, DPB1, DQA1 alleles, and DQB1*0603 status using molecular-based methods. Increased frequencies of DRB1*08 [odds ratio (OR) 7.7, 95% confidence interval (CI) 2.6-22.3], DRB1*11 (OR 3.1, 95% CI 1.2-8.1), DRB1*1301 (OR 7.7, 95% CI 2.6-22.3), DPB1*0201 (OR 3.5, 95% CI 1.6-8.0), DQA1*0103 (OR 4.4, 95% CI 1.5-13.3), DQA1*0501 (OR 2.9, 95% CI 1.3-6.6), DQA1*0601 (OR 30, 95% CI 3.6-241) and DQB1*0603 (OR 7.3, 95% CI 3.0-17.6) were found in the EOPA-JCA group compared with Caucasoid controls. Stratification of the EOPA-JCA group into antinuclear antibody (ANA) positive (n = 18) and ANA negative (n = 25) individuals revealed that ANA positivity was only associated with DRB1*1301 (OR 4.2, 95% CI 1.0-17.3), DPB1*0201 (OR 4.0, 95% CI 1.0-15.7) and DQB1*0603 (OR 11.5, 95% CI 2.5-53.4). Further analysis of the relative contributions of HLA antigens to ANA status revealed that DQB1*0603 determined the primary HLA effect. No apparent interaction between DQB1*0603 and DRB1*1301 or between DQB1*0603 and DPB1*0201 was found to contribute to the association with ANA. We suggest that those ANA positive individuals with a restricted HLA background, (DQB1*0603 positive), defines a group of EOPA-JCA patients which will be especially valuable in the characterization of the ANA associated with EOPA-JCA.

Age of Onset↗
PubMed1993

Impaired eye tracking in undergraduates with schizotypal personality disorder.

Qualitative ratings of smooth pursuit eye movements were significantly worse for 14 undergraduates with DSM-III-R schizotypal personality disorder than for 18 comparison subjects. The groups did not differ on IQ, indicating that deficits in smooth pursuit eye movements in schizotypal personality disorder are not a function of cognitive deficits.

Female↗
PubMed1992

Glomerular size and volume distributions for cranial, medial, and caudal divisions of domestic fowl kidneys.

Separate renal arteries and renal portal veins supply the three divisions of domestic fowl kidneys, leading to uncertainty concerning the structural and functional homology of the different divisions. To assess the degree of anatomical similarity, separate glomerular size and volume distribution profiles were constructed for cranial, medial, and caudal divisions from the left and right kidneys of male and female domestic fowl. There were no significant differences between left and right divisions (intradivision comparisons) or between cranial, medial, and caudal divisions (interdivision comparisons) when the total number of glomeruli or total glomerular volumes were compared on a per gram kidney weight basis. Glomerular size distribution profiles were unimodal in shape, with the peaks for all divisions falling in the 0.15-0.22 mm circumference range in males and in the 0.19-0.26 mm circumference range in females. There were no significant differences in glomerular size distribution profiles for intradivision (left vs. right) comparisons. Interdivisional comparisons revealed that medial divisions had significantly lower values than caudal divisions in one of 11 glomerular circumference categories. For all remaining comparisons, there were no significant differences in glomerular size distribution profiles, nor were there any significant interdivisional differences when glomerular volume distribution profiles were compared. These data indicate that the three divisions of domestic fowl kidneys are structurally homologous on a per gram kidney weight basis, suggesting the separate divisions also are functionally homologous.

Animals↗
PubMed1991

Peripheral nerve dysfunction in scleroderma.

Peripheral neuropathy in patients with scleroderma is thought to be rare. We have undertaken a quantitative assessment of peripheral nerve function in 29 patients with either limited cutaneous scleroderma or progressive systemic sclerosis. Tactile thresholds were raised in the fingers in 28 per cent of patients and in the foot in 50 per cent. Two-point discrimination was abnormal in 10 patients, thermal thresholds were abnormal in five and vibration thresholds were abnormal in one. Nerve conduction studies showed abnormalities in six patients, five of whom had clinical signs of a mild peripheral neuropathy: the mean duration of disease in these six patients was 10 years longer than that in the remainder of the patients. There was electrophysiological evidence of a subclinical carpal tunnel syndrome in two patients. The sympathetic skin response was recorded in 16 patients who had not been subjected to sympathectomy for Raynaud's phenomenon, and was abnormal in four. These results indicate that peripheral nerve dysfunction in scleroderma, though mild, is not as uncommon as previously thought. The abnormal cutaneous sensory thresholds may be partly due to altered viscoelastic properties of the skin, but abnormal responses in the lower limbs to tests of tactile sensitivity, the clinical findings and the disturbances of nerve conduction argue in favour of an additional neuropathic process in some patients. Low grade distal nerve trunk ischaemia may be responsible.

Adult↗
PubMed1989

Activity involvement, risk-taking, demographic variables, and other drug use: prediction of trying smokeless tobacco.

Four activity participation variables (clubs, sports, church, and parties); two indices of "risk-taking" (preference for risk-taking, getting into trouble at school); three demographic variables (sex, ethnic group, socioeconomic status); and two drug use variables (trial of cigarettes and alcohol) were examined as correlates and prospective predictors of trial of smokeless tobacco in two cohorts of seventh graders in urban Los Angeles. The data were analyzed separately for males and females. Cross-sectional logistic regression analyses indicated that correlates of trying smokeless tobacco among the seventh-grade cohorts or among these same cohorts in the eighth grade (considering those persons who had not tried smokeless tobacco in seventh grade) generally included being white, trying cigarettes, risk-taking, and attending parties. Prospective logistic regression analyses with data from subjects who had not tried smokeless tobacco in the seventh grade indicated that predictors of subsequent trial of it generally included only being white and having tried cigarettes. Sports participation predicted onset only in one cohort of female subjects but not in males. Some activities that have been proposed as being predictive of smokeless tobacco use (e.g., sports participation) are generally irrelevant for a large sample of young adolescents in urban Los Angeles. White male cigarette smokers, regardless of the activities they have engaged in, are most likely to try smokeless tobacco.

Adolescent↗
PubMed1986

Trends in self-poisoning with drugs in Newcastle, New South Wales, 1980-1982.

A review has been carried out of 747 cases of self-poisoning with drugs which were treated in the three major Newcastle hospitals over the three-year period 1980-1982. The data obtained have been compared with earlier published data for the years 1976-1979. The number of patients who were admitted to hospital fell from 290 in 1980 to 226 in 1982. The most common drugs used were benzodiazepine (34.5% of cases) and antidepressant agents (9.1%), paracetamol (7.9%), barbiturates (7.1%) and phenothiazines (3.8%). Although this indicated a gratifying drop in the use of barbiturate drugs, the use of several drugs in combination in self-poisoning rose disturbingly. Five patients died in hospital; 23 who committed suicide with drugs were not admitted to hospital but were investigated by the Regional Forensic Pathologist.

Acetaminophen↗
PubMed1985

Low-frequency septal stimulation increases tyrosine hydroxylase activity in the hippocampus.

Rats were chronically implanted with recording electrodes in the dorsomedial subiculum and stimulating electrodes in the septal area. Low-frequency septal stimulation (regular inter-pulse interval = 130 msec) was used over a period of 10 days to drive the hippocampal theta rhythm at 7.7 Hz (a régime shown previously to proactively facilitate acquisition of barpressing and retard its extinction), and high frequency (77 Hz) stimulation was used to block theta rhythm (a régime shown previously to proactively retard acquisition of barpressing and facilitate its extinction). The activity of soluble tyrosine hydroxylase from hippocampus increased in animals killed 15-33 days after the end of the period of 7.7 Hz septal stimulation but not after high-frequency stimulation. Irregular low-frequency stimulation with a mean inter-pulse of 130 msec produced the same effect on tyrosine hydroxylase activity as regular 7.7 Hz theta-driving. The possible relations between the effects of low-frequency septal stimulation on hippocampal tyrosine hydroxylase and on behavior are discussed.

Animals↗
PubMed1985

Proactive behavioral effects of theta-driving septal stimulation on conditioned suppression and punishment in the rat.

In two experiments, a treatment phase of septal stimulation preceded the acquisition of free operant lever pressing on a random-interval 64-s reinforcement schedule. Male Sprague-Dawley rats, chronically implanted with a bilateral septal stimulating electrode and a unilateral bipolar hippocampal recording electrode, received (a) low-frequency (7.7-Hz) stimulation, which drove the hippocampal theta rhythm, or (b) random-pulse stimulation (average frequency = 7.7 Hz), which produced only nonregular waveforms in the hippocampus. Control animals were implanted but not stimulated. After 12 days of lever-press acquisition, animals were presented while lever pressing with an auditory signal associated with a particular schedule of shock delivery: In Experiment 1, shocks occurred despite the subject's response strategy; in Experiment 2, shocks were delivered only if the rat pressed the lever. In both experiments, lever pressing was suppressed by the auditory stimulus. Theta-driving but not random-pulse septal stimulation proactively increased behavioral tolerance to the effects of electric shock. These results reinforce the idea that proactive behavioral effects of septal stimulation are a consequence of the production of the hippocampal theta rhythm.

Animals↗
PubMed1985

Handedness and alcoholism.

One hundred thirty-six alcoholic men and 48 alcoholic women admitted consecutively to an adult alcohol and substance abuse unit were studied in an attempt to replicate previous reports of an association between alcoholism and handedness. Each individual received a structured admission interview, and handedness was determined by a modification of the Edinburgh Inventory. Left-handedness was more frequent in men with alcoholic fathers and in first-born men. These data are discussed in the context of a recent theory relating left-handedness, immune disease, developmental learning disorders, and fetal testosterone.

Adult↗
PubMed1983

Proactive behavioral effects of theta-blocking septal stimulation in the rat.

The induction of hippocampal theta rhythm using low-frequency septal stimulation has been shown to proactively (1) facilitate the acquisition and (2) increase resistance to extinction of a food-rewarded fixed-ratio (FR) bar-press response (Holt & Gray, Quarterly Journal of Experimental Psychology, 35B, 97-118, 1983). Both (1) and (2) are also seen after septal lesions. This suggests that Holt and Gray's (1983) results may have been due either to stimulation-produced theta waves (the "theta" hypothesis), or a small septal lesion produced by the stimulating current (the "lesion" hypothesis). Both hypotheses were tested in the present experiment using high-frequency septal stimulation. In one of two treatment conditions male Sprague-Dawley rats, chronically implanted with a bilateral septal stimulating electrode and a unilateral bipolar hippocampal recording electrode, received (1) trains of continuous pulses at 77 Hz which blocked the hippocampal theta rhythm, or (2) trains of pulses at 100 Hz interrupted by a 30-msec interval at a frequency of 7.7 Hz. Control animals were implanted but not stimulated. Acquisition of a discrete-trial bar-press response on a fixed ratio 5 reinforcement schedule immediately followed the treatment phase. After 15 days' acquisition all animals were extinguished over the subsequent 12 days. Results indicated that both types of septal stimulation reduced resistance to extinction of barpressing; theta-blocking stimulation produced the greater effect. Theta-blocking stimulation retarded the acquisition of bar-pressing in the early stages of training. These overall results are exactly opposite to those produced by low-frequency (7.7 Hz) theta-driving septal stimulation (Holt & Gray, 1983) and contrary to the predictions of the lesion hypothesis. Furthermore, these findings support the idea that long-term changes in behavior may depend on stimulation-produced changes in the hippocampal theta rhythm.

Animals↗