Search PubMed⌕ Search

Biomedical subjects

N Cook

Publications and source records attributed to N Cook.

At least 91 records · Page 5Linked to original sources
PubMed1986

Extending the limits for modified Fontan procedures.

During the early development of atriopulmonary anastomotic operations (Fontan-Kreutzer), a number of physiologic and anatomical limits were proposed by the Fontan group as selection criteria. Among 167 consecutive patients undergoing modified Fontan procedures from 1973 through 1985, 109 (65%) patients exceeded one or more of the original selection criteria in areas of age, anomalies of systemic or pulmonary venous connection, pulmonary artery distortion, and pulmonary artery pressure. Twenty-six patients had a mean pulmonary artery pressure greater than 15 mm Hg, with 16 operative survivors (62%). Nineteen patients had anomalies of systemic and/or pulmonary venous connection, and 16 survived (84%). There were 44 patients under the age of 4 years, and 26 survived (59%). Twenty-five patients were older than 15 years, and 23 (92%) survived the Fontan procedure. Pulmonary artery distortion, relating to prior palliative operations, was found in 34 patients. Seventeen of these 34 survived a modified Fontan procedure (50%). Twenty-six patients had a pulmonary arteriolar resistance more than 2 Wood units times square meter, and 14 survived (54%), whereas 81 of 93 with a pulmonary arteriolar resistance of less than 2 U X m2 survived (87%). Multivariate analysis showed that pulmonary arteriolar resistance and pulmonary artery distortion had a significant, negative impact on survival, but age and anomalies of systemic and/or pulmonary venous connection did not. Pulmonary artery pressure was not an independent predictor of outcome. The results show that the original criteria may be exceeded in the areas of age and anomalies of pulmonary or systemic venous connection. Pulmonary artery pressure alone should not contraindicate a Fontan procedure if pulmonary arteriolar resistance is low. Pulmonary artery distortion from a prior palliative operation and elevated pulmonary arteriolar resistance increase the risk of a Fontan procedure.

Adolescent↗
PubMed1985

(-)-[125I]pindolol binding to the human platelet beta-adrenoceptor: characterisation and agonist interactions.

The binding of (-)-[125I]pindolol ((-)-[125I]PIN) to human platelet membranes has been examined and identifies a relatively low density of beta-adrenoceptor binding sites in this tissue. The relative order of potency of the catecholamines in displacement experiments, isoprenaline greater than adrenaline greater than noradrenaline and curve-fitting analysis of the competition binding isotherms using subtype selective beta-adrenergic antagonists, suggests the presence of an homogeneous population of beta 2-adrenoceptors. The effects of guanine nucleotides and mono- and divalent cations on the isoprenaline displacement of (-)-[125I]PIN binding to human platelet and rat lung membrane beta-adrenoceptors was compared in parallel experiments. In the presence of Mg2+ the agonist showed relatively lower overall affinity for the platelet receptor with a steep displacement curve, Hill slope approaching unity. Under these circumstances Gpp(NH)p characteristically produced a shift to the right and a steepening of the agonist displacement curve in rat lung but had no effect in platelet membranes. NaCl caused a parallel shift to the right of the curves in both systems in the presence or absence of Gpp(NH)p. The significance of these results in relationship to the efficiency of coupling of the human platelet beta-adrenoceptor to adenylate cyclase is discussed.

Adrenergic beta-Agonists↗
PubMed1985

A case-control study of BCG and childhood tuberculosis in Cali, Colombia.

We conducted a case-control study to evaluate the effectiveness of BCG vaccination in preventing childhood tuberculosis (TB) in Cali, Colombia. We ascertained 178 cases aged 0 to 14 years from the respiratory clinics with cough or fever for at least three weeks and a positive chest X-ray for TB, as well as 320 controls who were from the same households but had no symptoms and negative X-rays. Using matched set multiple logistic regression analysis, we found the age- and sex-adjusted relative risk (RR) of TB among vaccinees compared with non-vaccinees to be 0.84 with 95% confidence limits (CL) from 0.43 to 1.62. There was, however, a significantly lowered relative risk of TB with increasing time since vaccination (RR = 0.83 per year since time of vaccination with 95% CL from 0.74 to 0.94.)

Adolescent↗
PubMed1984

Comparison of the beta 1 selective affinity of prenalterol and corwin demonstrated by radioligand binding.

The ability of the beta 1 partial agonists prenalterol and corwin , to displace the binding of [3H]dihydroalprenolol to the heterogeneous populations of beta-adrenoceptors on rat and rabbit lung membranes was compared. Both drugs exhibited higher affinity for the binding sites in rabbit lung (predominant beta 1) as compared to rat lung (predominant beta 2). Curve fitting analysis of the displacement curves into high affinity (beta 1) and low affinity (beta 2) components indicates that both drugs exhibit beta 1 selective affinity. Further competition experiments performed in the presence of carefully calculated concentrations of highly selective beta 1 (atenolol) or beta 2 (ICI 118,551) antagonists to produce homogeneous receptor subtype populations in rat and rabbit lung membranes respectively, confirmed this beta 1 selective affinity. These results suggest an approximate selective affinity ratio (beta 1 to beta 2) of ten and forty fold for prenalterol and corwin respectively.

Adrenergic beta-Agonists↗
PubMed1984

The role of serotonin (5-HT) in the control of TSH and prolactin release in euthyroid subjects as assessed by the administration of ketanserin (5-HT2 antagonist) and zimelidine (5-HT re-uptake inhibitor).

We have studied the effects of ketanserin, a specific 5-HT2 antagonist, and zimelidine, a selective inhibitor of 5-HT re-uptake into central nervous system presynaptic terminals, upon basal and TRH stimulated serum TSH and prolactin levels in euthyroid individuals. Ten normal volunteers were studied (five male and five female), each receiving oral ketanserin and oral zimelidine during respective seven day periods, separated by an interval of at least two weeks. A standard TRH test (200 micrograms i.v.) was carried out before and after each period of drug administration, serum samples being obtained for TSH and prolactin estimation. We were unable to demonstrate any modification of basal or TRH-stimulated TSH and prolactin levels by the oral administration of either ketanserin or zimelidine, suggesting that 5-HT has no significant role in the physiological release of either TSH or prolactin.

Female↗
PubMed1984

Circadian rhythms of serum thyrotrophin and body temperature in euthyroid individuals and their responses to warming.

The diurnal rhythms of body temperature and serum thyrotrophin (TSH) levels in euthyroid individuals behaved inversely to one another. An artificially induced rise in the body temperature of these individuals was accompanied by a fall in serum thyrotrophin levels, the amplitudes of their respective rhythms decreasing simultaneously. There was a marked correlation between the degrees of change in body temperature and circulating thyrotrophin levels respectively during warming. In normal subjects manipulation of the diurnal rhythm of body temperature brings about inverse alterations in the thyrotrophin rhythm.

Body Temperature↗
PubMed1984

Circulating catecholamine, thyrotrophin, thyroid hormone and prolactin responses of normal subjects to acute cold exposure.

The responses of circulating catecholamines, TSH, thyroid hormones and prolactin to 30 min of acute cold exposure (4 degrees C) were measured in eight normal volunteers over a 2 h period. There was a rise in circulating noradrenaline, TSH, T4 and T3 levels and a fall in circulating prolactin in the subjects studied, but no change in circulating adrenaline levels nor any alteration in the T4/T3 ratio. The thyroid axis of normal individuals can respond rapidly to acute cold exposure. In addition, the increased plasma noradrenaline levels accompanied by unaltered adrenaline levels suggest that the stimulus exerted by cold does not evoke a generalised stress response, but rather that the sympathetic nervous system is selectively stimulated.

Adult↗
PubMed1984

Capnocytophaga ochracea infection: two cases and a review of the published work.

Bacteria of the genus Capnocytophaga are recently recognised pathogens which may cause oral disease and subsequent septicaemia in the immunocompromised host. We present two cases of infection caused by Capnocytophaga ochracea; a soft tissue infection in an immunologically normal patient and an episode of septicaemia in a child with leukaemia. The microbiology, pathogenicity, and antimicrobial susceptibility of the genus capnocytophaga are reviewed.

Bacterial Infections↗
PubMed1983

Sun exposure habits in patients with cutaneous melanoma: a case control study.

Telephone interviews were conducted with 111 patients with cutaneous melanoma and 107 controls to determine sun-exposure habits during various life periods. Painful or blistering sunburns during either childhood or adolescence were associated with subsequent increased risk of developing cutaneous melanoma. While solar exposure does not appear to be a factor in some patients, when patients were divided into subgroups by age, sex, or sun type, each subset showed some increased risk associated with a factor related to short-term excessive sun exposure. Ill effects due to such exposures appeared to increase the risk of melanoma.

Adult↗
PubMed1978

Cryosurgery of headache.

The use of cryosurgery applied to the sphenopalatine area (artery and ganglion) plus the superficial temporal and occipital branches of the external carotid artery has proven worthwhile in a majority of patients in whom this procedure has been used since 1968. Experience includes almost 700 procedures in more than 500 patients who have answered to follow-up. The procedure is not a major operation, is repeatable and, until the ideal drug is discovered, offers a better than average change for definite improvement in vascular headache.

Animals↗
PubMed1975

Thermal properties of cancellous bone.

Specimens of beef bone were analyzed for thermal conductivity and thermal capacity. The thermal conductivity was about 7 X 10(-4) cal/cm/sec/degrees C, that is about the same as for other tissues. As regards thermal capacity, the determination of 0.73 cal/cm2/degrees C also was similar to that in other tissues. Both thermal conductivity and capacity were isotropic with respect to the layer of epiphyseal cartilage, and the orientation of bony trabeculae. Thermal probes were devised heated either by water or by electric current to destroy localized volumes of bone, as in surgery. To achieve necrotizing temperatures, the sizes of such probes and the times of application of heat were determined.

Animals↗