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Biomedical subjects

P Fletcher

Publications and source records attributed to P Fletcher.

At least 73 records · Page 4Linked to original sources
PubMed1986

Synthesis of 2',3'-O-(2,4,6-trinitrocyclohexadienylidine)guanosine 5'-triphosphate and a study of its inhibitory properties with adenylate cyclase.

A fluorescent GTP analog 2',3'-O-(2,4,6-trinitrocyclohexadienylidine) guanosine 5'-triphosphate (TNP-GTP) has been prepared and some of its physical properties characterized. TNP-GTP was found to be a potent inhibitor of chick embryo heart adenylate cyclase as activated by guanyl 5'-(beta,gamma-imido)triphosphate (GppNHp), F-, and forskolin with Ki values in the 8-15 microM range. It also appeared to inhibit substantially basal adenylate cyclase in this system. TNP-GTP demonstrated an effective competition with [3H]GppNHp, binding to membranes equivalently to GppNHp and about three times better than GTP. 8-Azidoguanosine 5'-triphosphate (8N3GTP) mimics GTP activation of chick embryo heart adenylate cyclase and [gamma-32P]8N3GTP is effectively photoincorporated into a 42,000- to 44,000-Mr doublet when proteins are separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. TNP-GTP effectively prevents this photoincorporation, as does GTP, at concentrations that agree with their respective apparent inhibition and activation binding constants. The data suggest that TNP-GTP could prove to be a valuable tool for studying the mechanisms of GTP regulation of adenylate cyclase and other GTP-regulated systems.

Adenylyl Cyclase Inhibitors↗
PubMed1986

Onset of right-to-left shunting through a foramen ovale in a 70-year-old woman: successful surgical treatment.

A 70-year-old woman presented with disabling breathlessness. She was found to have severe arterial hypoxaemia due to isolated right-to-left shunting through a patent foramen ovale. In the absence of pulmonary hypertension or evidence of right ventricular dysfunction this is attributed to reduced right atrial compliance. The phasic nature of the shunt, which occurred only during atrial filling, supports this view. Surgical closure of the foramen abolished the hypoxaemia and her symptoms.

Aged↗
PubMed1986

The effects of diabetes mellitus, exercise, and single doses of biguanides upon lactate metabolism in man.

The polymorphism of phenformin oxidation has been investigated in 103 non-insulin-dependent (Type II) diabetics. The frequency distribution was clearly bimodal and 14 poor metabolisers were identified. The frequency of the recessive allele (0.369) was not significantly different from that found previously in non-diabetics. Six of the extensive metabolisers of phenformin were matched for age, sex and oxidizer phenotype with non-diabetic controls. All subjects underwent a standard 3-min exercise test, using a bicycle ergometer, after which plasma lactate concentration was monitored for 90 min. There was no significant difference between groups in lactate accumulation or elimination. Ten extensive metabolisers, ten poor metabolisers and seven non-diabetics (matched for age, sex and phenotype with seven of the diabetic extensive metabolisers) were challenged with a fasting oral dose of phenformin (50 mg), after which plasma lactate, and blood pyruvate and glucose concentrations were monitored for 4 h. A further ten diabetics (five extensive and five poor metabolisers of phenformin) received a single dose of metformin (1 g) following an identical protocol. No significant changes were observed in any group.

Adult↗
PubMed1986

Self-association of local anaesthetic drugs in aqueous solution.

The aggregation characteristics of a series of local anaesthetic drugs in water and electrolyte solution have been examined using total intensity light scattering, photon correlation spectroscopy and vapour pressure osmometry. The association of cinchocaine hydrochloride was micellar. An appreciable increase in the effective diffusion coefficient as solutions of cinchocaine were diluted close to the critical micelle concentration was observed and has been discussed. The association of amethocaine hydrochloride could be described using a co-operative stepwise association model. No association could be detected in water or 0.1 mol dm-3 electrolyte for butacaine hemisulphate and the hydrochlorides of procaine, proparacaine, mepivacaine, lignocaine, bupivacaine and prilocaine at drug concentrations of less than 0.2 mol dm-3.

Anesthetics, Local↗
PubMed1984

Classification of the vertical component of furcation involvement.

The current classifications of teeth with furcation involvements refer mainly to the horizontal component of bone loss. This article presents a subclassification that measures the probeable vertical depth from the roof of the furca apically. The subclasses being proposed are: A, B and C. "A" indicates a probeable vertical depth of 1-3 mm, "B" 4-6 mm and "C" 7 or more mm of probeable depth from the roof of the furca apically. Furcations would thus be classified as IA, IB, IC, IIA, IIB, IIC and IIIA, IIIB, IIIC.

Alveolar Process↗
PubMed1983

Nosocomial surgical infections: incidence and cost in a developing country.

Eight hundred twenty-nine patients were monitored for nosocomial surgical infections from January to December 1980 at the University Hospital of the West Indies. Two hundred twenty-five patients (27%) had 189 postoperative wound infections (POWI) and 295 other nosocomial infections, with an average of 2.1 infections per infected patient. The incidence of POWI was 22.8%, varying from 7.3% in clean to 82.2% in infected wounds. The most common organisms isolated were gram-negative bacilli and Staphylococcus aureus. The most frequent nosocomial infection other than POWI was urinary tract infection (27.8%). A statistically significant number of urinary tract infections and septicemias were associated with the use of medical devices such as indwelling urethral catheters and central venous pressure lines (p less than 0.001). Septicemia was frequently associated with operations on the lower gastrointestinal and hepatobiliary tracts (p less than 0.001). The postoperative stay of an infected patient was prolonged by an average of 18 days. The total excess cost of hospitalization for the infected patients was U.S. $170,000.

Cross Infection↗
PubMed1982

Hemodynamic improvement after peritoneovenous shunting in nephrogenic ascites.

A patient being treated by regular hemodialysis for end-stage renal failure had nephrogenic ascites. Despite attempts at fluid removal by ultrafiltration, progressive hypotension and low cardiac output eventually reduced fistula flow so much that hemodialysis became almost impossible. The insertion of a peritoneovenous shunt resulted in reduction of ascites and 78% increase in cardiac output, with consequent correction of hypotension and improvement of fistula flow. Peritoneovenous shunting is a simple and beneficial form of treatment for nephrogenic ascites that does not respond to fluid removal by dialysis.

Ascites↗
PubMed1982

Temporary regression during language acquisition: a linguistic analysis of a 2 1/2-year-old child with epileptic aphasia.

A 2 1/2-year-old child suffered a brief and temporary regression of speech, with complete recovery, on two separate occasions. During the second episode, clinical evaluation and electroencephalographic data led to the diagnosis of epileptic aphasia. The child's conversations at home were tape-recorded by the mother during the acute phase of the disorder and the recovery period, and transcripts of the conversations were analysed by means of a linguistic profile. These analyses confirmed the clinical improvement in the child's language abilities, which occurred within a few days. This case illustrates the remarkably specialised and localised cerebral function which underlies speech production at an early age. It indicates that this function can be interfered with selectively and temporarily, without any significant effect on general behaviour.

Aphasia↗
PubMed1982

Favorable effects of therapy on cardiac performance in spontaneously hypertensive rats.

To determine whether chronic antihypertensive therapy reduces cardiac mass and improves performance in spontaneously hypertensive rats (SHR) with marked left ventricular hypertrophy and evidence of cardiac dysfunction, 12-mo-old male and female SHR and age- and sex-matched normotensive rats (NORM) were treated for 6 mo with either tap water or tap water containing hydralazine or guanethidine. Cardiac performance was assessed by the peak stroke volume and cardiac indices attained during volume loading and by the maximum left ventricular pressure developed during an aortic occlusion. Passive diastolic pressure-volume curves were obtained in the potassium-arrested heart. Treatment prevented the progression of left ventricular hypertrophy in SHR and the marked deterioration in peak pumping ability observed in untreated male SHR and the modest impairment observed in female SHR. The peak developed pressure of both the male and female treated SHR was reduced toward that of NORM and was associated with a reduction in the left ventricular mass-to-volume ratio toward that of NORM. Thus chronic therapy with either hydralazine or guanethidine reduced cardiac mass and prevented the deterioration in cardiac pumping performance observed in SHR with sustained hypertension and marked cardiac hypertrophy.

Aging↗