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Biomedical subjects

K Hall

Publications and source records attributed to K Hall.

At least 271 records · Page 15Linked to original sources
PubMed1982

Dependence of 4'-(hydroxymethyl)-4,5',8-trimethylpsoralen photoaddition on the conformation of ribonucleic acid.

The photoaddition of 4'-(hydroxymethyl)-4,5',8-trimethylpsoralen (HMT) to different conformational states of RNA was studied. Poly(U), poly(A,U) (random copolymer), poly(A-U) (alternating copolymer), poly(A) . poly(U) (double stranded), and poly(U) . poly(A) . poly(U) (triple stranded) were reacted with HMT at different temperatures and salt concentrations. The conformation of the polymers was monitored by UV absorption and circular dichroism. It was found that the rate of HMT photoaddition changed dramatically at structural transitions in the RNA. The alternating copolymer poly(A-U) was found to have the highest rate of addition. Low salt and temperature produced maximal incorporation.

Circular Dichroism↗
PubMed1982

Hyperprolactinaemia in men-response to bromocriptine therapy.

Men with hyperprolactinaemia present with large tumours. Conventional therapy with surgery and/or irradiation is unsatisfactory, with up to 100% of patients remaining hyperprolactinaemic (or subsequently developing pituitary insufficiency). In view of reports of bromocriptine-induced regression of prolactinomas, eight consecutive male hyperprolactinaemic patients with impotence and/or symptoms related to local tumour effects were treated with bromocriptine 20 mg daily as sole therapy for 3-11 months. Symptoms were relieved partly or completely in seven patients and serum prolactin was restored to normal or near normal in all men. Serum thyroxine and plasma cortisol response to hypoglycaemia became normal in two men who had subnormal values before therapy. Mean serum growth hormone response to hypoglycaemia rose significantly as did plasma testosterone concentrations. Evidence of tumour regression, sometimes massive, was seen in the six patients who underwent repeat radiology. The symptomatic relief and biochemical and radiological improvement in these patients indicate that bromocriptine therapy may now be the treatment of choice for hyperprolactinaemic men with large tumours.

Adult↗
PubMed1982

A gas chromatographic mass spectrometric assay for plasma trifluoperazine concentrations following single doses.

A gas chromatography mass spectrometric assay using selected ion monitoring is described which permits the determination of trifluoperazine in plasma at concentrations ranging from 0.078 to 5.0 ng ml-1. It relies on the extraction of trifluoperazine and the internal standard, prochlorperazine or the tetradeuterated analogue of trifluoperazine, from basified plasma with a n-pentane/2-propanol solvent mixture. Following the evaporation of organic solvent, the residue is reconstituted in a small volume of methanol. Suitable aliquots were analysed by the combined technique of gas chromatography/electron impact mass spectrometry with a data system. The described procedure is specific and enables the quantitation of 78 pg ml-1 of the drug with a coefficient of variation less than 7%. The method has demonstrated sufficient sensitivity to permit pharmacokinetic and bioavailability studies after a single 5 mg oral dose.

Biological Availability↗
PubMed1982

Somatomedins in aging and dementia disorders of the Alzheimer type.

Serum levels of somatomedins were determined in apparently healthy aged individuals and dementia patients primarily with clinically suspected Alzheimer type disorder. Serum somatomedin values, determined by radioreceptorassay and radioimmunoassay, fell with advancing age in normal subjects. A significant elevation in serum somatomedins was observed in dementia patients. CSF somatomedin levels were also increased in the only two patients with suspected Alzheimer type disease examined. Since somatomedins are believed to act as anabolic hormones, it was suggested that the elevated levels represent a compensatory mechanism to overcome receptor insensitivity in patients with dementia disorders of the Alzheimer type.

Aged↗
PubMed1982

The distribution of somatomedins in the nervous system of the cat and their release following neural stimulation.

Recent evidence suggests a regulatory role in the nervous system for somatomedins. The present study, using a somatomedin radioreceptorassay which primarily detects insulin-like growth factors 1 and 2, shows that somatomedins are widely distributed throughout the nervous system of the cat. Whilst somatomedins were present in all CNS regions, the highest concentration occurred in the hypothalamus followed by cerebral cortex. In the spinal cord, the dorsal roots contained twice the concentration found in the ventral roots. Activity was also present in the sympathetic ganglia, vagus nerve and sciatic nerves. Following electrical stimulation of the brachial and sciatic nerves somatomedins were released into perfusates from extirpated cut limbs. These findings suggest that somatomedins may be neuroregulatory hormones.

Animals↗
PubMed1982

A ligand-binding assay for thyroxine-binding globulin based on polyethylene glycol separation.

A simple ligand-binding assay for thyroxine-binding globulin (TBG) is described. The method depends on the partition of labelled thyroxine between bovine serum albumin and TBG. Differentiation between labelled thyroxine bound to TBG and bovine serum albumin is achieved by the addition of excess TBG antiserum and subsequent precipitation with polyethylene glycol. The results are compared with the Corning Immophase kit method for TBG.

Humans↗
PubMed1982

Head injury rehabilitation: benefit of early intervention.

Severely head injured patients in an acute rehabilitation setting were retrospectively divided into early and late rehabilitation admission groups (admitted before and after 35 days post injury). The 2 groups consisted of 16 and 20 patients respectively and were matched for length of coma, age, level of disability, neurosurgical procedures required, and other factors which might bias results due to less morbidity in the early admission group. Findings indicated that late admission patients required twice as much acute rehabilitation as early admission patients, even though both groups were comparable in initial disability and at outcome 2 years post-injury. Study findings implied potential cost savings of an average $40,000 per patient for acute hospital care. These benefits may be due to improved neurologic outcome or prevention of secondary complications.

Adult↗
PubMed1981

Bromocriptine therapy for "nonfunctioning" pituitary tumors.

Bromocriptine therapy may cause regression of prolactinomas, but its effect on nonsecretory pituitary tumors is uncertain. Conventional treatment for such "functionless" tumors is surgery and/or radiotherapy, but recurrences pose a therapeutic dilemma. We describe a patient with such a tumor treated by surgery and radiotherapy who presented with recurrent disease 14 days later. On treatment with bromocriptine, 20 mg daily for 25 months, the intrasellar tumor recurrence had diminished in size and a suprasellar extension had almost disappeared. Bromocriptine therapy may therefore benefit some patients with nonsecretory pituitary tumors considered unsuitable for surgery or radiotherapy.

Adenoma, Chromophobe↗
PubMed1981

Comparison of gas-liquid chromatography and EMIT assay for serum valproic acid.

We describe a simple direct extraction method for the gas-liquid chromatography determination of serum valproic acid. The working range for the assay is 2-180 mg/L and our within-run precision was 5.8 and 4.3% at the 40 and 90 mg/L concentrations respectively. Hemolyzed and lipemic sera as well as samples from patients with hyperbilirubinemia and from patients with decreased renal function were put through the assay and no interfering peaks were noted. Interference occurred when teflon-lined screw caps were used during the extraction step. The method was proven to be accurate by linear regression analysis of samples containing weighed-in amounts of valproic acid. The above assay was compared to an enzyme immunoassay technique (EMIT). The working range for the latter is 10-150 mg/L and the with-run precision was 10.8 and 5.9% and 90 mg/L concentration respectively. Samples were run by both the gas-liquid chromatograph and enzyme immunoassay methods and gave very similar results over the range 16-139 mg/L.

Bilirubin↗
PubMed1981

Human embryonic somatomedin.

A radioreceptor assay utilizing human fetal brain plasma membrane as matrix and somatomedin A as ligand (fetal brain RRA-SMA) was developed. Increased levels of fetal brain RRA-SMA were found in the fetal circulation. The concentration was approximately 4-fold higher in the fetal as compared to the adult human. At birth, values fell within the adult range. In contrast, adult somatomedins determined by somatomedin radioimmunoassay were undetectable in the fetus and below the adult range at birth. Levels of fetal brain RRA-SMA were decreased in fetuses with different clinical disorders. In healthy newborns at cesarean section a significant correlation between serum fetal brain RRA-SMA values and birth weight and length was found. These results indicate the presence of an embryonic somatomedin in humans. The fetal brain RRA-SMA may provide a reliable index of fetal growth.

Adult↗
PubMed1981

Evoked potentials and head injury. 1. Rating of evoked potential abnormality.

This paper describes a method for rating the degree of abnormality of auditory, visual and somatosensory evoked potential patterns in head injury (HI) patients. Criteria for judging degree of EP abnormality are presented that allow assessment of the extent and severity of subcortical and cortical dysfunction associated with traumatic brain damage. Interrater reliability data based upon blind ratings of normal and HI patients are presented and shown to be highly significant. Tables of normative values of peak latencies and amplitudes are given and illustrations of EP patterns of different degrees of abnormality are presented.

Adolescent↗
PubMed1981

Evoked potentials and head injury. 2. Clinical applications.

The method of rating abnormality of evoked brain potential patterns and assessing the extent and severity of cortical and subcortical brain dysfunction in head injury patients described in Part I is applied in a clinical context. Evoked potential abnormality (EPA) scores are found to be significantly correlated both with admission and outcome disability approximately one year after head injury. Correlations increase with the increase in the number of sensory modalities tested. Correlations between EPA scores and clinical disability (measured by the Disability Rating Scale) decrease with time after injury. Significant correlations, however, persist for about 60 days after onset of injury. It was found that EP pattern abnormalities can reflect specific sensory (and at times motor) deficits in noncommunicative patients and thereby contribute significantly to early treatment and rehabilitation planning.

Adolescent↗
PubMed1981

Plasma pattern of immunoreactive ACTH in normal man and in patients with Nelson's syndrome.

A radioimmunoassay for ACTH determinations in human plasma was developed using an N-terminal antiserum. Plasma ACTH levels at 6 a.m. in 39 patients with normal pituitary-adrenal function were below 4 pmol/l in two individuals. The remaining had a mean of 32.7 +/- 4 pmol/l (n = 37). Gel filtration on Sephadex G-50 medium and G-75 revealed that a high molecular weight immunoreactive ACTH was found in plasma from both normal individuals and patients with Nelson's syndrome. The stimulation of ACTH secretion with metyrapone (750 mg perorally) significantly increased the mean plasma levels of 1-39 ACTH after 3 h (from 0.9 to 6.6 pmol/l) in 10 healthy individuals. The level of the high molecular weight form remained constant. In one patient with Nelson's syndrome hydrocortisone iv (100 mg/h for 3 h) suppressed the total ACTH levels from 360 to 83 pmol/l following corticoid withdrawal on the previous evening, but did not affect the high molecular weight form of ACTH. The difference between the amounts of immunoreactive ACTH found in plasma from normal individuals and from patients with Nelson's syndrome was attributed to 1-39 ACTH.

Adrenocorticotropic Hormone↗