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Biomedical subjects

J C Shaw

Publications and source records attributed to J C Shaw.

At least 37 records · Page 2Linked to original sources
PubMed1998

Adrenal function in preterm infants: ACTH may not be the sole regulator of the fetal zone.

The fetal zone of the adrenal gland is known to persist after preterm birth, but there is uncertainty as to how long adrenal fetal zone steroid production continues and how it is regulated. The purpose of this study was to test two hypotheses. First, that the urinary excretion of 3beta-OH-5-ene steroids persists until term, and then declines, as it does in full-term infants. Second, that the persistence of the fetal zone is due to continuing ACTH stimulation. A longitudinal observational study was undertaken in 22 preterm infants of 24-31-wk gestation. Sequential measurements were made of urinary 3beta-OH-5-ene steroids (fetal zone steroid metabolites), plasma dehydroepiandrosterone sulfate (DHEAS), and ACTH. Excretion of urinary 3beta-OH-5-ene steroids was 1500-2000 microg kg(-1) d(-1), persisting until term, and declining abruptly at approximately 42 wk postconceptional age (PCA), to levels comparable to term infants at the same PCA. Median plasma ACTH levels rose from <7.6 pg mL(-1) at 25-wk PCA to 34.5 pg mL(-1) at 46-wk PCA. Urinary 3beta-OH-5-ene steroids were highest when ACTH levels were lowest, and were declining when ACTH was rising. In four infants given dexamethasone, urinary excretion of 3beta-OH-5-ene steroids and plasma DHEAS were not suppressed fully, when plasma ACTH and cortisol, and urinary cortisol metabolites were. These data suggest that ACTH is not the sole regulator of the adrenal fetal zone steroid synthesis and that involution of the fetal zone is related to gestation rather than birth.

Adrenal Glands↗
PubMed1996

Intention as a component of the alpha-rhythm response to mental activity.

Many studies of alpha-rhythm reactivity conclude that alpha is selectively attenuated by attention accompanying mental activity. The topography of this attenuation is assumed to match the relevant functional topography of the cortex. But there are reports of apparent increased attention resulting in no change, or even enhanced alpha - the paradoxical response. It is proposed that in this case, alpha amplitude may be dependent on an intention component of behaviour. Some conflicting reports of alpha reactivity to mental processes may then be resolved. It is argued that the classical attention model of alpha is untenable, except for simple sensori-motor responses. Reasons are given to support this and the concept of intention as a neuropsychological variable is introduced. Evidence is presented for a generalisation of an oculomotor model of alpha activity proposed by Wertheim who demonstrated that alpha reduces during attentive, but not during intentive visual behaviour. The generalisation follows from reports of enhanced alpha in the few seconds prior to a skilled action in sport, and by neurophysiological evidence for a separate cortical organisation for perception and action. Varying proportions of attention and intention then add a dimension to the factors influencing alpha blocking which may explain its inconsistent response.

Adult↗
PubMed1996

Antiandrogen and hormonal treatment of acne.

In the treatment of acne in women, the use of antiandrogens and other hormonal approaches is a valuable alternative to standard therapy. These treatments that are based on physiologically sound principles produce gratifying results in selected women with acne, and are the primary treatment for women with hirsutism. The drugs discussed in this article include spironolactone, cyproterone acetate, flutamide, oral contraceptives, corticosteroids, finasteride, and gonadotropin-releasing hormone agonists. Patient selection, pretreatment evaluation, and case studies also are discussed with an emphasis on practical applications.

Acne Vulgaris↗
PubMed1996

Activity of the adrenal fetal zone in preterm infants continues to term.

In term babies, steroids from the fetal zone of the adrenal gland decline in the blood and urine in the first few weeks after birth. In infants born prematurely, fetal zone steroids (3 beta-OH-5ene steroids) persist but it is not known for how long. The present study set out to address this by examining changes in the synthesis and metabolism of adrenal steroids with postconceptional age, using serial measurements of steroid metabolites in the urine. 21 preterm infants, median gestation 29 weeks (range 24-31 weeks) and median birth weight 933g were examined. 3 beta-OH-5ene steroids represented around 90% of the total steroids excreted until 2 weeks past term, falling to 55% by 12 weeks after term. 3 beta-OH-5ene steroids were excreted in the urine at levels of 1500-2000 micrograms kg-1 d-1, until 3-4 weeks past term, after which these urinary fetal zone steroid metabolites declined, falling to 500 micrograms kg-1 d-1 six weeks past term. We conclude that activity of the adrenal fetal zone in preterm infants continues to term, after which it diminishes. This suggests that it is gestation that determines fetal zone activity rather than birth.

Adrenal Cortex↗
PubMed1994

Accuracy of ultrasound in a screening programme for abdominal aortic aneurysms.

OBJECTIVES: To assess the accuracy of ultrasound in the measurement of aortic diameter. SETTING: A general practice based screening programme for abdominal aortic aneurysm. DESIGN: (a) comparison of ultrasound with computed tomography (CT) measurement; (b) two period crossover study to assess interobserver error; (c) comparison of ultrasound measurements by technicians and radiologists. RESULTS: In 36 patients where CT showed clear maxima in anteroposterior diameter, the measurement by ultrasound was consistently less than by CT scan (mean ultrasound-CT difference -4.4 mm, range -12.3 to 2.4 mm). There was no difference in the measurements made by different ultrasonographers, but their method of measurement produced a reading for aortic diameter less than that obtained by a vascular radiologist. CONCLUSIONS: These results show that ultrasound measurement is less accurate for smaller aneurysms, consistently gives a smaller reading for aortic diameter when compared with CT measurement, but was reproducible between ultrasonographers. Monitoring and audit of aneurysm screening programmes to assess accuracy and reproducibility of ultrasound measurement is recommended.

Aged↗
PubMed1991

Spironolactone in dermatologic therapy.

In the treatment of androgen-mediated skin disorders spironolactone provides a valuable therapeutic option. This article reviews the use of spironolactone as an antiandrogen in dermatologic therapy. The endocrinologic effects, pharmacology, dermatologic uses, and side effects are discussed, and guidelines for its use are provided.

Acne Vulgaris↗
PubMed1991

Distribution of dihydrolipoamide acetyltransferase (E2) in the liver and portal lymph nodes of patients with primary biliary cirrhosis: an immunohistochemical study.

The reason for the close association between primary biliary cirrhosis and the appearance of antibodies that recognize the E2 component of pyruvate dehydrogenase complex is not understood. The distribution of the three pyruvate dehydrogenase complex subunits was examined in the liver and lymph nodes of patients with primary biliary cirrhosis, patients with other liver diseases and normal subjects by immunohistochemistry using affinity-purified antibodies. Intensity of staining was assessed semiquantitatively and validated by scanning laser confocal microscopy. In primary biliary cirrhosis tissue, the E2 staining pattern did not parallel the reported distribution of mitochondria. E2 staining in biliary epithelial cells was consistently stronger than in hepatocytes. In primary biliary cirrhotic liver, staining of biliary epithelium was significantly stronger than in normal or other liver disease controls; many bile ducts in primary biliary cirrhotic liver demonstrated very high intensity, diffuse distribution of stain. No differences in staining intensity were seen between perivenular hepatocytes in primary biliary cirrhotic liver and those in controls; periportal hepatocytes in primary biliary cirrhotic liver were, however, more intensely stained than perivenular cells. In primary biliary cirrhotic portal lymph nodes, a subset of macrophages showed high-intensity, diffuse distribution of stain. By contrast, staining with antibodies to E1 and E3 (other components of pyruvate dehydrogenase complex) produced uniform-intensity, mitochondrial distribution both in primary biliary cirrhosis and control tissue. The increased intensity of E2 in primary biliary cirrhotic tissue could be explained in terms of abnormal metabolism of E2 by biliary epithelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetyltransferases↗
PubMed1991

Upper extremity contractures in a patient with eosinophilia-myalgia syndrome.

L-tryptophan is an essential amino acid taken as an over-the-counter nutritional supplement for a variety of conditions including chronic pain, insomnia, and depression. In October 1989 several patients were reported having eosinophilia-myalgia syndrome (EMS) who had taken L-tryptophan in large doses. Little is known about the long-term outcomes of EMS. A patient with EMS who developed contractures of the upper extremities because of severe myalgias is discussed. Early aggressive rehabilitative intervention may prevent contractures in patients with EMS.

Arm↗
PubMed1990

Virilisation of female preterm infants.

Two cases of hypertrophy of the clitoris in premature girls are reported; this was associated with persistently high concentrations of adrenal fetal zone androgens.

Adrenocorticotropic Hormone↗
PubMed1989

Sporotrichosis in the acquired immunodeficiency syndrome.

Kaposi's sarcoma and disseminated sporotrichosis of the skin and joints developed simultaneously in a homosexual man with antibodies to human immunodeficiency virus. There was no identified source of exposure to Sporothrix organisms. Sporotrichosis may be a presenting opportunistic infection associated with acquired immunodeficiency syndrome and tends to be disseminated at the time of diagnosis.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Nonmetabolizable base balance: effect of diet composition on plasma pH.

The pH of the plasma is determined by the concentration and chemical properties of the acids and bases dissolved in it. Three classes of acids and bases can be identified: 1) carbonic acid (CA), formed by intermediary metabolism and disposed of principally by pulmonary ventilation--variation in the rate of pulmonary ventilation controls the plasma concentration of CA; 2) metabolizable acids (MA) are either absorbed from the diet or arise in the process of intermediary metabolism and are mainly disposed of by intermediary metabolism; 3) nonmetabolizable acids and bases (NB) are absorbed from the diet and are disposed of by renal mechanisms, which also control their concentration in the plasma. Growing infants and children are in positive balance for NB, and about 96% of it is laid down in the skeleton. Because of their dietary origin and disposal in the urine, it is possible to measure the balance of nonmetabolizable acids and bases using conventional metabolic balance techniques. This is particularly important for the development of diets for young infants, as their renal mechanisms for the control of the concentration of plasma nonmetabolizable acids and bases are immature and easily overcharged. The lack of published data, however, makes it impossible to recommend maximum and minimum intakes of nonmetabolizable base.

Acid-Base Equilibrium↗