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Biomedical subjects

A White

Publications and source records attributed to A White.

At least 307 records · Page 17Linked to original sources
PubMed1990

Some clinical approaches to the homeless mentally ill.

Clinicians who work with homeless people are likely to encounter a very broad spectrum of mental disorders and residential patterns. As with any other patient population, the particulars of clinical interventions must be guided by the specific constellations of biological, psychological, and social needs. However, for individuals who not only suffer from serious psychiatric disorders, but are also homeless, effective approaches may require significant modifications of traditional techniques and changes in the prioritization, timing, and framing of specific interventions. In this article we will focus on people who are severely and persistently mentally ill and who have been sleeping for months or years in shelters or in public spaces such as parks, streets, and bus terminals.

Chronic Disease↗
PubMed1990

Coexistence of mucinous cystadenoma of the ovary and ovarian sarcoidosis.

A case of ovarian and systemic sarcoidosis with mucinous cystadenoma coexisting in the same ovary is described. This association has not been previously reported. The differentiation of systemic sarcoidosis from metastatic spread of ovarian cancer and from sarcoid-like reactions in regional lymph nodes of tumors is discussed.

Adult↗
PubMed1990

The synthesis of ACTH and related peptides by tumours.

Despite all we have learned, the reason why certain tumours and particularly non-pituitary tumours synthesize ACTH remains an enigma. There is no clear theory which links the neoplastic process with the expression of peptide hormones but it is interesting to speculate that the amplification of certain oncogenes may be linked to de-repression of hormone genes. Once the gene has been switched on, there should be some mechanism for preventing continuous expression and in the pituitary the POMC gene is normally inhibited by glucocorticoids. Therefore it is crucial to investigate the role of glucocorticoids in non-pituitary tumours and this requires an understanding of the molecular mechanisms involved in glucocorticoid inhibition of the normal POMC gene in the pituitary. The evidence presented in this chapter describing the glucocorticoid receptor binding site in the promoter region of the POMC gene in rat pituitary gives an exciting insight into the regulatory mechanisms and their potential for aberrant control. Taken with the presence of pituitary-specific regions regulating the POMC gene promoter there appear to be multiple approaches to dissecting out the differences in non-pituitary tumours. Thus in a relatively short period of time there has been a marked increase in our understanding of the molecular mechanisms underlying POMC gene expression. At the level of the peptides, progress has been slower. We are now aware that secretion of ACTH implies that a number of other peptides will be found in the circulation, even though there is limited evidence for a specific role for any of the co-secreted peptides. However, it is hard to understand the conflicting reports that N-POC is synthesized by non-small cell and small cell carcinoma of the lung when ACTH, which we assume to be co-secreted, is thought to be synthesized only by small cell carcinoma. The most likely explanation for this is the difficult nature of the radio-immunoassays for these hormones and the problems associated with studying large groups of clearly defined patients. Development of very simple methods for measuring the ACTH precursors has demonstrated that they are released into the circulation in normal subjects and that the levels are markedly elevated in non-pituitary tumours, suggesting that they are the major circulating forms in the ectopic ACTH syndrome. This implies that these tumours cannot process the precursor molecules suggesting that the processing enzymes are lacking.(ABSTRACT TRUNCATED AT 400 WORDS)

ACTH Syndrome, Ectopic↗
PubMed1990

Adrenal function after upper femoral fracture in elderly people: persistence of stimulation and the roles of adrenocorticotrophic hormone and immobility.

Previous work has shown persistent elevations in plasma cortisol concentration following upper femur fracture in elderly people. To investigate this phenomenon further, we measured plasma cortisol and adrenocorticotrophin (ACTH) and performed overnight dexamethasone suppression tests in carefully characterized patients and controls (mobile and immobile). There was no difference in cortisol or ACTH, either basally or after dexamethasone, between the mobile and immobile controls. At 2 and 8 weeks after injury, basal plasma cortisol was significantly higher than in either control group and was not related to an index of the patients' mobility potential. The ACTH concentrations also tended to be raised after injury, but the differences in concentration between injured and control subjects did not reach statistical significance. At both 2 and 8 weeks after injury, the post-dexamethasone cortisol concentration was significantly higher in the fracture patients, particularly the least mobile. Our results show that the elevation in plasma cortisol concentration in elderly femur-fracture patients, which may persist for at least 8 weeks after injury, is not explained by immobility and is probably mediated by an increased central drive to the hypothalamic-pituitary-adrenal axis.

Adrenal Cortex↗
PubMed1990

The laryngeal mask airway in pediatric radiotherapy.

The use of the laryngeal mask airway, a new form of airway, is described in infants and young children receiving radiotherapy under general anesthesia. The laryngeal mask airway consists of a tube, at the distal end of which is attached an elliptically shaped cuff resembling a miniature face mask. The laryngeal mask is inserted blindly into the pharynx, and its cuff forms a low pressure seal around the larynx through which the patient can breathe spontaneously. No complications occurred during use of the laryngeal mask in 25 children who received 312 anesthetics. This experience suggests that the laryngeal mask airway has a valuable role in this situation and may contribute to the safety of anesthesia.

Anesthesia, General↗
PubMed1990

High lumbar disc degeneration. Incidence and etiology.

Three hundred seventy-nine consecutive magnetic resonance images (MRIs) with dual-echo images of the entire lumbar spine were reviewed by the authors. All 379 patients presented with back pain and/or leg pain; they were interviewed and examined. Pain drawings were completed by all. There were 42 patients (11.1%) with disc pathologies involving T12-L1, L1-2, and/or L2-3 levels. Six patients (1.6%) had isolated disc degeneration and/or herniations limited only to these high lumbar segments. The remaining 36 patients had degenerative changes of the higher discs with variable involvement of the lower lumbar discs. Out of 12 spondylolistheses of L5 on S1, 7 had high disc pathologies at one or more levels presenting as skipped lesions; more severe high disc lesions were noted in Grade II slips. Isolated high disc degeneration is often associated with pre-existing abnormalities such as end-plate defects, Scheuermann's disease, limbus vertebra, and so forth, and stressful cumulative work activities such as in construction workers, airplane mechanics, and so forth. High disc degeneration was noted above or below previous fractures. High disc involvement with diffuse changes in lower lumbar spine was more commonly found in ascending fashion in older age groups, and in patients who have had previous lower lumbar spine surgeries, prior fusions in particular. Our findings suggest that altered mechanics are associated with the high lumbar disc pathologies.

Adult↗
PubMed1990

Metabolic bone disease in lumbar pseudarthrosis.

Pseudarthrosis occurs in many patients who undergo lumbar spine fusion and it has been suggested that abnormalities of bone metabolism contribute to it. The authors evaluated 47 patients with pseudarthrosis for metabolic bone disease. Symptomatic patients with pseudarthrosis underwent metabolic bone evaluation. Abnormal results of laboratory tests were found in 7 patients (14.9%): 3 low or borderline 1,25 dihydroxy vitamin D3, 2 elevated 24-hour urine calcium, and 2 low serum testosterone. None of these abnormalities correlated with other clinical findings. Bone density was low in 14 of 24 patients in whom it was measured. Low values did not correlate with smoking or abnormal laboratory values. Metabolic bone abnormalities do not appear to play a frequent or significant role in pseudarthrosis after attempted lumbar spine fusion.

Adult↗
PubMed1990

Burns from iodine.

Explore the source record for details and available documents.

Burns, Chemical↗
PubMed1990

The effect of oxytocin infusion on adenohypophyseal function in man.

The responses of the adenohypophyseal hormones adrenocorticotrophin (ACTH), growth hormone (GH), thyroid stimulating hormone (TSH), prolactin, luteinizing hormone (LH) and follicle stimulating hormone (FSH) to sub-maximal doses of hypothalamic releasing factors were studied in six lean male volunteers (age 23-35 years) with and without infusions of oxytocin (OXT). OXT infusion (mean plasma concentration 133.6 +/- 2.6 pmol/l) completely inhibited the plasma ACTH responses to corticotrophin releasing hormone (CRH) (saline, peak increment ACTH 1.61 +/- 0.75 pmol/l; OXT, peak increment ACTH - 0.04 +/- 0.28 pmol/l; P less than 0.05). OXT infusion had no significant effect on the GH response to growth hormone releasing hormone (GHRH), the TSH and prolactin responses to thyrotrophin releasing hormone (thyroliberin, TRH) or the LH and FSH responses to gonadotrophin releasing hormone (luteoliberin, GnRH). The data support a role for OXT in the modulation of ACTH secretion in man.

Adrenocorticotropic Hormone↗
PubMed1990

Patterns of ACTH and cortisol pulsatility over twenty-four hours in normal males and females.

Patterns of plasma ACTH and cortisol concentrations were studied in 10 healthy subjects (five male, five female in the early follicular phase, overall age range 21-32 years) by sampling through an indwelling cannula every 15 min for 24 h. The subjects were in hospital, ambulant, and taking normal meals. Plasma ACTH was measured by a two-site immunoradiometric assay with a detection limit of 3.9 ng/l (0.9 pmol/l). Pulses were identified by the method of Clayton et al. (1987) using stringent criteria to minimize false positive peaks. All subjects showed a circadian rhythm of ACTH, the acrophase occurring between 0615 and 0920 h in all but one subject and the mesor value was between 9.2 and 18.6 ng/l (2.0 and 4.1 pmol/l). There were significantly fewer pulses between 1800 and 2400 h compared with the other three 6-h periods. The pattern of ACTH differed between males and females in several respects: more pulses (18 vs 10), greater mean peak amplitude (16.8 vs 10.3 ng/l), greater area under the 24-h profile (350.9 vs 206.6 ng/l h) and higher mean level (14.7 vs 8.6 ng/l) in the males. In contrast, the cortisol pattern did not show statistically different sex differences. The sex differences suggest greater sensitivity to, or availability of, ACTH to the female adrenal cortex, or different set points in cortisol feedback.

Adrenocorticotropic Hormone↗
PubMed1990

The responses of arginine vasopressin and adrenocorticotrophin to nausea induced by ipecacuanha.

Ipecacuanha syrup induces emesis by an early peripheral (gastric irritant) action and a later central effect at the chemoreceptor trigger zone (CTZ). We have studied the responses of plasma AVP, ACTH and ACTH-precursors to early and late ipecacuanha-induced nausea in nine healthy male subjects. Symptom severity was assessed using a linear analogue scale. All subjects reported 'early' nausea (N1) with a latency of 16 +/- 2 min (mean +/- SEM) and eight subjects vomited. Six subjects experienced recurrent nausea (N2) (latency 106 +/- 10.4 min) of whom five also vomited. The interval between the cessation of N1 and the onset of N2 was 55 +/- 10.8 min (range 25-80 min). The severity of nausea at the onset of N1 or N2 was similar but the AVP and ACTH responses were highly variable. Thus, while mean plasma AVP concentrations increased during both symptom periods, in three subjects during N1 and in three subjects during N2 plasma AVP concentrations did not rise above the normal range, despite marked symptoms. No clear pattern of AVP response to distinguish early peripheral from late central ipecacuanha-induced emesis was demonstrated. Whilst mean plasma ACTH concentrations increased during both N1 and N2 there were no changes in mean plasma ACTH-precursor concentrations. Analysis of pooled data for N1 and N2 demonstrated direct correlations between the nausea score and the peak incremental plasma responses of either AVP or ACTH and, despite the variability, peak incremental concentrations of AVP and of ACTH were also correlated. The data indicate that there is no difference in the AVP responses to peripherally or centrally stimulated ipecacuanha-induced nausea.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1990

Seminal peroxidase positive cells are not an adequate indicator of asymptomatic urethral genital infection.

The relationship between asymptomatic urethral infection and seminal white blood cells, as detected using the peroxidase enzyme system, was examined. Eighty-four semen donors were tested. Twenty-four (29%) were diagnosed as having an active urethral genital infection. There was no statistical relationship between the total number of concentrations of peroxidase-positive cells and a urethral genital infection. Further studies should concentrate on the subtypes of seminal leucocytes and their surface receptors using monoclonal antibodies.

Humans↗
PubMed1990

Psychological profile of the atopic eczema patient.

A survey of 40 patients with long-standing atopic eczema was carried out to test for the presence of certain psychological traits which had been reported in studies in earlier decades. A series of standardised personality tests was administered to these patients and the results compared with the findings for a normal group for each test. It was demonstrated that atopic eczema patients do have significantly high levels of anxiety and problems in dealing with anger and hostility. Whether such findings make any contribution to understanding the aetiology of this disorder is debatable, but they do have implications for treatment and management, and some of these are discussed.

Adolescent↗
PubMed1990

The role of alpha-2-adrenoceptors in the control of ACTH secretion; interaction with the opioid system.

This study examined the effects of an alpha-2-adrenoceptor antagonist on the secretion of ACTH basally and in response to the opioid antagonist naloxone, which is known to stimulate ACTH secretion by an adrenergic mechanism. Eight normal men were given, in double-blind, random order, intravenous infusions of normal saline (placebo), idazoxan (alpha-2-adrenoceptor antagonist), naloxone and the combination of idazoxan and naloxone. Naloxone increased plasma ACTH and cortisol concentrations in comparison to placebo. Idazoxan significantly enhanced the ACTH and cortisol responses to naloxone but had no effect on plasma ACTH or cortisol concentrations when given alone. These findings suggest that during some conditions of increased ACTH secretion, inhibitory alpha-2-adrenoceptors are activated and that these receptors limit the ACTH response. This provides an explanation for some of the apparent contradictions in interpreting the data from previous studies on the effects of catecholamines on the secretion of ACTH.

Adrenergic alpha-Antagonists↗
PubMed1990

ACTH adrenal cell bioassay: improved sensitivity (12 ng/L) achieved by immunoextraction of ACTH from human plasma by a monoclonal antibody.

We have previously reported a bioassay for human plasma ACTH based upon trypsin dispersed guinea-pig adrenal cells which was sensitive to 100 ng/L ACTH in unextracted human plasma when measured against human pituitary ACTH (1-39) standard 74/555. We now present a bioassay of increased sensitivity (12 ng/L) which incorporates three major changes. The trypsin/trypsin inhibitor step in the cell dispersion protocol has been replaced with collagenase, donor calf serum (3%) has been incorporated into the standard curve and ACTH has been extracted from human plasma and dilutions of standard hormone by a sephacryl bound monoclonal antibody (2A3) directed towards the 25-39 sequence. The extracted standard curve has a detection limit of 6 ng/L and the cells can tolerate up to 50% plasma equivalent concentration. Thus, the improved assay has a detection limit of 12 ng/L ACTH in plasma. The assay can now measure bioactive plasma ACTH levels reliably in the normal range.

Adrenal Glands↗