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Biomedical subjects

K Craig

Publications and source records attributed to K Craig.

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

Changes in atrial natriuretic peptide and plasma renin activity following changes in right atrial pressure in patients with chronic renal failure.

Since it was first discovered in the early 1980s, the role of atrial natriuretic peptide (ANP) in the control of fluid and electrolyte balance and blood pressure has been extensively studied in both health and disease. We report here a study of ANP and its relationship to corresponding changes in right atrial pressure (RAP) in patients with chronic renal failure (CRF) on haemodialysis compared to healthy controls. Although there was a positive correlation between RAP and ANP in both groups, the changes in ANP following changes in RAP between the two groups were not statistically significant. A unique observation was the response of RAP to changes in posture, with RAP falling significantly as expected in healthy controls in contrast to the exceptional absence of a significant fall in patients with CRF. Healthy controls demonstrated appropriate postural changes in plasma renin activity (PRA) despite marked suppression of PRA levels due to salt loading, in complete contrast to patients with CRF who, despite chronic fluid overload and elevated levels of ANP, continued to have grossly elevated PRA levels that failed to change significantly in response to changes in posture.

Atrial Function, Right↗
PubMed1995

Nephrotic syndrome and acute renal failure associated with hepatitis A virus infection.

Acute renal failure has been documented in association with hepatitis A virus (HAV) infection. This report describes a temporal relationship between HAV infection and immune complex mesangial proliferative glomerulonephritis associated with nephrotic syndrome. Animal experimental data have already shown that this is indeed a histological lesion associated with HAV infection. This case report is the first English documentation associating HAV infection with immune complex mesangial proliferative glomerulonephritis.

Acute Kidney Injury↗
PubMed1994

Luteal phase defect: the sensitivity and specificity of diagnostic methods in common clinical use.

OBJECTIVE: To assess the sensitivity and specificity of common clinical tests used for the diagnosis of luteal phase defect (LPD). DESIGN: The sensitivity and specificity of these tests for predicting low integrated P levels over the luteal phase were calculated. SETTING: Outpatient reproductive endocrinology and infertility clinic at a university medical center. PATIENTS: Fifty-eight strictly defined normal women were used to determine normal integrated luteal phase P levels. The study population was a separate 34 women who either were normal (n = 15) or were being evaluated for infertility or recurrent abortion (n = 19). These 34 study subjects all had the following tests performed in the same menstrual cycle: daily reproductive hormone levels, daily assessment of preovulatory follicle size, late luteal endometrial biopsies, and BBT charts. MAIN OUTCOME MEASURES: Basal body temperature, maximum preovulatory follicle size, dated endometrial biopsies, and serum P levels (single and multiple) were used in an attempt to predict which patients had low integrated P levels. RESULTS: Unacceptably low sensitivity and/or specificity levels were found for the following tests: appearance of BBT charts, luteal phase length, and preovulatory follicle diameter. Timed endometrial biopsy was found to have marginally acceptable sensitivity and specificity levels whether dated by next menstrual period or midcycle events. The best test for the prediction of low integrated P was a single serum P level from the midluteal phase that was < 10 ng/mL (31.8 nmol/L) or a sum of three random serum P measurements that was < 30 ng/mL (95.4 nmol/L) (also obtained in the midluteal phase). CONCLUSIONS: Luteal phase defect is a relatively uncommon but important cause of infertility and/or habitual abortion. The recommended test for the determination of LPD is a midluteal phase single serum P level < 10 ng/mL or the sum of three serum P levels that is < 30 ng/mL. The endometrial biopsy is a second line test that is only recommended when LPD needs to be evaluated in a treated cycle (ovulation induction or supplemental P).

Abortion, Habitual↗
PubMed1994

Utilization of uniformly labeled 13C-polyunsaturated fatty acids in the synthesis of long-chain fatty acids and cholesterol accumulating in the neonatal rat brain.

Polyunsaturated fatty acids are needed for normal neonatal brain development, but the degree of conversion of the 18-carbon polyunsaturated fatty acid precursors consumed in the diet to their respective 20- and 22-carbon polyunsaturates accumulating in the brain is not well known. In the present study, in vivo 13C nuclear magnetic resonance spectroscopy was used to monitor noninvasively the brain uptake and metabolism of a mixture of uniformly 13C-enriched 16- and 18-carbon polyunsaturated fatty acid methyl esters injected intragastrically into neonatal rats. In vivo NMR spectra of the rat brain at postnatal days 10 and 17 had larger fatty acid signals than in uninjected controls, but changes in levels of individual fatty acids could not be distinguished. One day after injection of the U-13C-polyunsaturated fatty acid mixture, 13C enrichment (measured by isotope ratio mass spectrometry) was similar in brain phospholipids, free fatty acids, free cholesterol, and brain aqueous extract; 13C enrichment remained high in the phospholipids and cholesterol for 15 days. 13C enrichment was similar in the main fatty acids of the brain within 1 day of injection but 15 days later had declined in all except arachidonic acid while continuing to increase in docosahexaenoic acid. These changes in 13C enrichment in brain fatty acids paralleled the developmental changes in brain fatty acid composition. We conclude that, in the neonatal rat brain, dietary 16- and 18-carbon polyunsaturates are not only elongated and desaturated but are also utilized for de novo synthesis of long-chain saturated and monounsaturated fatty acids and cholesterol.

Aging↗
PubMed1993

Supraventricular tachycardia, right atrial pressure, atrial natriuretic peptide and polyuria--a necessary sequence?

The release of atrial natriuretic peptide (ANP) may be stimulated by tachycardia and the evidence from human studies suggests that this is mediated by a rise in atrial pressure. However, animal experiments suggest that tachycardia can by itself increase ANP levels without increasing right atrial pressure (RAP). We report here the case of a healthy volunteer who had supraventricular tachycardia (SVT) whilst participating in a study evaluating the relationship between changes in RAP and changes in ANP. The ANP levels rose following the SVT but there was no rise in RAP, suggesting that heart rate can modulate ANP levels without changes in RAP as has been shown in animal experiments.

Adult↗
PubMed1993

Neuropsychological prediction of treatment efficacy and one-year outcome in schizophrenia.

The present study was conducted to establish the degree of interrelationship between neuropsychological functioning in the acute phase of the schizophrenic illness, clinical measures of treatment response (positive and negative symptoms), and 1-year outcome. Nineteen SADS/RDC schizophrenic inpatients were clinically rated during a 2-week drug washout period and again following 4 weeks of neuroleptic treatment. The findings revealed that reduced attentional ability in the baseline phase significantly predicted the presence of higher residual negative symptoms following 4 weeks of treatment, while neurocognitive status was unrelated to positive symptom response. With respect to prediction of the 1-year outcome, poor functional status of this schizophrenic population was significantly associated with the presence of baseline memory dysfunction.

Adult↗
PubMed1991

The effects of selective beta-adrenoceptor antagonists and partial agonist activity on renal function during exercise in normal subjects and those with moderate renal impairment.

1. The effects of sustained moderate exercise in the sitting position on renal haemodynamics and glomerular filtration were measured in six normotensive patients with moderately impaired renal function and seven age-matched normal volunteers. 2. The changes in the effects of exercise on renal function induced by chronic cardioselective beta-adrenoceptor blockade by drugs with (epanolol) and without intrinsic sympathomimetic activity (atenolol) were examined. 3. Both beta-adrenoceptor blockers attenuated the heart rate increase with exercise, but only atenolol lowered blood pressure significantly. In resting volunteers on atenolol, associated with the fall in blood pressure there was a significant reduction in glomerular filtration rate. 4. Glomerular filtration fell significantly in all groups with exercise, and renal blood flow also fell in parallel. These changes were not influenced by drug treatment. 5. The exercise-induced rise in PRA was suppressed by atenolol but not by epanolol. 6. The renal function and haemodynamic responses to moderate exercise does not appear to be mediated by the systemic renin-angiotensin system or by beta 1-adrenoceptors.

Adrenergic beta-Agonists↗
PubMed1991

Effects of exercise on renal function in patients with moderate impairment of renal function compared to normal men.

The renal excretory and haemodynamic responses to sustained moderate exertion were investigated in normotensive humans with impaired renal function and normal volunteers. The heart rate increase with exercise was similar in each group. Subjects with impaired renal function showed a significant fall in glomerular filtration rate on exertion, while normals did not. In the presence of renal disease, urine osmolality did not rise with exertion, although it rose markedly in the normal group. Free water clearance became negative after exercise in the normal group only. The diseased kidney is unable to maintain glomerular filtration rate or conserve water under the stress of exertion as well as the normal kidney.

Adult↗
PubMed1989

Frusemide, ACE inhibition, renal dopamine and prostaglandins: acute interactions in normal man.

1. The acute effects of intravenous frusemide (30 mg) on prostaglandin dependent renal haemodynamics, urinary prostaglandin excretion, urinary dopamine excretion and electrolyte excretion were studied in six salt replete healthy volunteers with and without pretreatment with the angiotensin converting enzyme (ACE) inhibitor, ramipril (5 mg) and compared with the effects of ramipril alone in order to clarify the role of the renin-angiotensin system in these responses. 2. Frusemide increased natriuresis (UNaV), kaliuresis (UKV), inulin clearance and plasma renin activity (PRA) and ramipril pretreatment significantly enhanced these effects suggesting that the acute generation of angiotensin II (AII) may attenuate these actions of intravenous frusemide. 3. Frusemide increased para-aminohippurate (PAH) clearance, osmolar clearance and urine flow but did not change filtration fraction or urinary kallikrein excretion. Pretreatment with ramipril did not affect these responses. 4. Frusemide increased the excretion of urinary PGE2 and 6-keto-PGF1 alpha. Ramipril pretreatment did not suppress this rise in prostaglandin excretion. Since the frusemide induced prostaglandin dependent renal haemodynamic changes were also not suppressed with ACE inhibition, this suggests that in salt-replete volunteers AII does not significantly modulate renal prostaglandin production after frusemide. 5. Urinary free dopamine excretion increased with frusemide alone. With ramipril pretreatment this rise showed a tendency to increase. AII may therefore inhibit the rise in urinary dopamine excretion after frusemide. However this requires further study.

Adult↗
PubMed1989

Evidence against a role for prostaglandins in sustaining renal hyperfiltration in type 1 diabetes mellitus.

The acute effect of inhibition of prostaglandin synthesis with indomethacin 50 mg by mouth on renal haemodynamics has been examined in 8 male Type 1 diabetic patients with elevated glomerular filtration rate who were free of diabetic complications. Renal plasma flow and glomerular filtration rate were measured by constant infusion of para-amino hippurate and polyfructosan, the patients being studied at normoglycaemia. Urinary excretion of prostaglandin E2 fell from 885 +/- 160 to 345 +/- 115 pg min-1, and excretion of 6-keto-prostaglandin F1 alpha fell from 489 +/- 77 to 283 +/- 50 pg min-1. There was no change in renal plasma flow or glomerular filtration rate following indomethacin. The results do not support the hypothesis that increased renal prostaglandin synthesis is a cause of hyperfiltration in diabetes mellitus.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

The acute renal haemodynamic and endocrine response to felodipine in normal man.

Felodipine (0.075 mg/kg p.o.), a calcium antagonist, was given to 9 male volunteers, with and without indomethacin pretreatment. Diuresis and natriuresis occurred after felodipine without significant change in effective renal plasma flow or glomerular filtration rate. There was no significant change in urinary 6 keto PGF 1 alpha or urinary kallikrein excretion and indomethacin did not inhibit the natriuretic or diuretic response to felodipine. The felodipine induced diuresis and natriuresis appears most likely to be mediated by an action of the drug on renal tubules.

Adult↗
PubMed1982

Ventilation and perfusion alterations following homologous blood transfusion.

A previous study in this laboratory examined the effect of micropore ultrafiltration of blood products on pulmonary gas exchange and subsequent pulmonary dysfunction--related morbidity and death. Morbidity and death from pulmonary failure was not affected; however, gas exchange was improved following ultrafiltration with 40 micrometers filters, as reflected by lower Bohr dead-space fractions. This difference might be explained by reduction of the microaggregate load seen in the pulmonary microvasculature. The purpose of this study was to examine in more detail these gas exchange alterations, paying particular attention to the correlation of changing Bohr dead-space ventilation detected with multiple inert gas analysis with direct determinations of microaggregate size and number. Fourteen patients with isolated cutaneous thermal injury scheduled for major early burn would excision were selected for study. Following transfusion with homologous blood products, the ventilation/perfusion ratio (Va/Q) distributions determined by inert gas analysis remained essentially unchanged except for subtle changes in both high VA/Q and dead-space compartments, resulting in significantly increased Bohr dead-space fractions (P less than 0.05). This combination of gas exchange alteration is consistent with vasoactive and occlusive changes in the pulmonary microvasculature following microaggregate infusion. The correlation of changing dead-space ventilation with the total microaggregate load was poor (r = 0.15) but was significant when compared with counts of microaggregates greater than 90 micrometers in diameter (r - 0.85). These findings suggest that gas exchange alterations following blood transfusion are primarily reflected by increased dead-space ventilation secondary to vasoconstriction and occlusion of the pulmonary microvasculature with microaggregates greater than 90 micrometers in diameter.

Adolescent↗
PubMed1980

Metabolite gene regulation of the L-arabinose operon in Escherichia coli with indoleacetic acid and other indole derivatives.

The ability of indole derivatives to facilitate RNA polymerase transcription of the L-arabinose operon in Escherichia coli was shown to require the catabolite activator protein (CAP) as well as the araC gene product. Adenosine 3',5'-monophosphate (cAMP) was not obligatory for araBAD transcription when the cells were grown in the presence of 1 mM indole-3-acetic acid or in the presence of indole-3-acetamide, indole-3-propionic acid, indole-3-butyric acid, or 5-hydroxyindole-3-acetic acid. However, these indole derivatives were unable to circumvent the cAMP requirement for the induction of the lactose and the maltose operons. Catabolic repression occurred when glucose was added to cells grown in the presence of L-arabinose and 1 mM indoleacetic acid or 1 mM cAMP. This effect was reversed at higher concentrations of indoleacetic acid or cAMP. The induction and the catabolite repression phenomena were quantitated by measuring the differential rate of synthesis of L-arabinose isomerase (the araA gene product). These results indicated that indole metabolites from various living systems may regulate gene expression and may be involved in "metabolite gene regulation."

Arabinose↗
PubMed1975

Personality characteristics in heroin addicts and nonaddicted prisoners using the Edwards Personality Preference Schedule.

The present study compares the self-reported personality characteristics of heroin addict and nonaddict prisoners using the Edwards Personality Preference Schedule (EPPS) which was corrected for social desirability. Seventy pairs of addicted and nonaddicted criminal offenders were matched for age, education, intelligence, and home environment. The addicted offenders were identified by the pattern of their response to the EPPS as reflected by the significant multivariate results. In addition, significant univariate differences consistent with those previously reported were found. Addicted criminals had stronger succorance, heterosexuality, and aggression needs and less abasement and endurance needs than nonaddicted offenders. Age, educational achievment, intelligence,and home environment had little influence on the prisoners' response to this self-report personality inventory.

Adult↗