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Biomedical subjects

D Baldwin

Publications and source records attributed to D Baldwin.

At least 73 records · Page 4Linked to original sources
PubMed1995

Relationship of isokinetic peak torque with work and power for ankle plantar flexion and dorsiflexion.

Past research has analyzed the relationship of peak torque with work and power on the muscles surrounding the knee with correlation coefficients being reported, ranging from .67 to .99. No studies to date have examined this relationship for muscles surrounding the ankle joint. The purpose of this study was to analyze the relationship of peak torque with work and power for the plantar flexor and dorsiflexor muscles of the ankle. Isokinetic data were collected from 15 healthy subjects (six males, nine females; mean age = 26.6 years) on an isokinetic dynamometer across two trials at speeds of 30 and 120 degrees/sec. The results of Pearson product moment correlations between peak torque to work and peak torque to power indicated correlation coefficients ranging from .81 to .97 for all speeds of testing and angular velocities. These findings suggest that peak torque is representative of work and power.

Adult↗
PubMed1995

Interconnecting the personal and public: the support networks of public health nurse Mona Wilson.

The life of public health nurse Mona Gordon Wilson reveals the importance of women's private lives in explaining their public activities. Although Mona's life and personality were also shaped by her gender, class, ethnicity, single status, and place in the patriarchal society, this article contends that female networking and support groups were essential to her success as a public person. Following a brief synopsis of the highlights of Mona's public life, this study examines the importance of female networking and support groups in Mona Wilson's early years as a nursing student, in her years overseas with the American Red Cross, as chief public health nurse on Prince Edward Island, and in retirement and old age.

Female↗
PubMed1994

Lack of efficacy of fluoxetine in recurrent brief depression and suicidal attempts.

Recurrent brief depression (RBD) fulfills DSM-III-R symptom criteria for major depression but the episodes are of shorter duration than the 2 weeks required by DSM-III-R. The clinical importance of the disorder has been observed in prophylactic studies of suicidal behavior. The possibility that antidepressants with selective action on the reuptake of serotonin might be effective in preventing recurrences of brief depression has been investigated. Fluoxetine in a dose of 120 mg a week, administered biweekly, had no effect on the recurrence rate, which was maintained at approximately the same rate on fluoxetine (1 every 18.7 days) as with placebo (1 every 17.6 days). In a group of patients with two or more prior episodes of suicidal behavior, there were 18 attempted suicides in the 54 patients treated with fluoxetine and the same number in the 53 patients treated with placebo. Fluoxetine neither raised nor lowered the suicide attempt rate as compared with placebo, providing no evidence to support the drug's role in either suicide provocation or prevention. Since fluoxetine is clearly effective with recurrent major depression, it would appear that recurrent brief depression has a different pharmacology.

Bipolar Disorder↗
PubMed1994

Molecular cloning of a novel human cDNA encoding a zinc finger protein that binds to the interleukin-3 promoter.

The CT/GC-rich region (-76 to -47) is one transcriptional regulatory region of the interleukin-3 (IL-3) gene which confers basic transcriptional activity and responds to trans-activation by human T-cell leukemia virus type I-encoded Tax. We isolated three types of cDNAs encoding Cys2/His2-type zinc finger proteins that bind to this region. Two were identical to known transcription factors, EGR1 and EGR2, and the other clone, named DB1, encoded a novel protein of 516 amino acids with six zinc finger motifs. DB1 mRNA was present in human tissues, ubiquitously. Two constitutive transcripts of 4.0 and 4.8 kb in length were present in Jurkat cells. Electrophoretic mobility shift assay, with specific antibodies, showed that DB1 constitutively binds to this region whereas EGR1 binds in a T-cell activation-dependent manner. Overexpression of DB1 in Jurkat cells had no detectable effect on the transcription activity of the IL-3 promoter, in a transient-transfection assay. EGR1 and EGR2 increased IL-3 promoter activity when the transfected cells were stimulated with phorbol-12-myristate-13-acetate and A23187. When DB1 was cotransfected with a Tax expression vector, transcription activity of the IL-3 promoter induced by Tax was significantly increased, while EGR1 and EGR2 were without effect. These results suggest that EGR1 has a role in inducible transcription of the IL-3 gene, while DB1 sustains basal transcriptional activity and also cooperates with Tax to activate the IL-3 promoter.

Amino Acid Sequence↗
PubMed1994

Cross refractoriness between sodium metabisulphite and exercise induced asthma.

BACKGROUND: Exercise and inhaled sodium metabisulphite are thought to cause bronchoconstriction in asthma through different mechanisms. The response to both stimuli becomes refractory with repeat challenge. The mechanism of refractoriness is unclear, although depletion of mast cell derived mediators or neurotransmitters has been suggested. Recent studies suggest a common mechanism involving release of inhibitory prostaglandins. If this is true, exercise and sodium metabisulphite induced bronchoconstriction should show cross refractoriness. METHODS: Thirteen subjects with mild asthma and previously established exercise and sodium metabisulphite induced bronchoconstriction performed two sodium metabisulphite challenges (giving a single dose previously shown to cause a 20% fall in FEV1) on one study day, and two exercise tests on another. The second challenge proceeded after recovery (FEV1 > 95% baseline) from the first. Subjects then attended on two further occasions when an exercise test was performed after sodium metabisulphite and a sodium metabisulphite challenge after exercise. RESULTS: When expressed as the percentage reduction in the area under the change in percentage FEV1 curve over 20 minutes (AUC) the response to exercise was reduced by a mean 62.3% (95% CI 46.5% to 78.1%) following a first exercise challenge, and by 50.7% (95% CI 27.8% to 73.6%) following a sodium metabisulphite challenge. The response to a sodium metabisulphite challenge was reduced by a mean of 80.2% (95% CI 68.9% to 91.5%) when it followed a sodium metabisulphite challenge, and by 37.3% (95% CI 15.1% to 59.5%) following an exercise challenge. CONCLUSION: This study shows some cross refractoriness between exercise and sodium metabisulphite induced bronchoconstriction, in keeping with a partially shared mechanism of refractoriness.

Adolescent↗
PubMed1994

The levels of clarithromycin and its 14-hydroxy metabolite in the lung.

Clarithromycin is a new macrolide that has a longer half-life than erythromycin and is claimed to reach higher tissue concentrations. We aimed to investigate whether, following oral administration, the drug and its 14-hydroxy metabolite reach levels in lung tissue that are likely to be clinically effective against common respiratory pathogens. Ten patients undergoing diagnostic bronchoscopy received seven doses of clarithromycin, 500 mg b.i.d. orally. Bronchoscopy was performed at a mean time of 4.25 h after the last dose. At bronchoscopy, bronchial biopsies and bronchoalveolar lavage were performed. Clarithromycin and its 14-OH metabolite were measured in serum, bronchial biopsies, epithelial lining fluid (ELF) and alveolar cells. Mean levels of clarithromycin were 4.0 mg.l-1 in serum, 16.8 mg.kg in bronchial biopsies, 20.5 mg.l-1 in ELF and 372.7 mg.l-1 in alveolar cells. The equivalent levels of 14-OH metabolite were 0.7, 2.7, 1.9 and 38.6 mg.l-1, respectively. We conclude that there is considerable concentration of clarithromycin and its 14-OH metabolite in alveolar cells, and to a lesser extent in bronchial tissue and ELF; this implies efficacy against susceptible organisms at these sites.

Clarithromycin↗
PubMed1994

Pentoxifylline therapy for chronic claudication: are patients dependent on therapy?

BACKGROUND: The purpose of this study was to evaluate the efficacy of long-term pentoxifylline therapy. METHODS: Fifty consecutive patients on long-term pentoxifylline therapy entered a weaning program. The standard dose of 400 mg three times a day was reduced to 400 mg twice a day for 1 month, 400 mg daily for an additional month, and then withdrawn completely for 3 months. Subjective evaluation of each patient's symptoms and objective measurements (treadmill testing for initial claudication distance, maximum walking distance, and ankle/brachial indexes) were evaluated during treatment withdrawal. RESULTS: Twenty-seven patients tolerated withdrawal of therapy without symptomatic deterioration. Seven of nine patients who did not tolerate weaning had deterioration of treadmill ICD/MWD parameters; there was a significant absolute decrease (p = 0.016) in MWD from 430 +/- 78 to 221 +/- 23 feet. Patients with an initial low MWD were less likely to tolerate weaning. Sixty percent of the patients with successful weaning had clinically asymptomatic deterioration of treadmill ICD/MWD parameters. CONCLUSIONS: A substantial number of patients who have been on long-term successful pentoxifylline therapy for claudication can be weaned from the drug. Asymptomatic deterioration of treadmill test parameters is not an indication for resuming therapy.

Aged↗
PubMed1993

Mapping the stability determinants of bacterial tyrosyl transfer RNA synthetases by an experimental evolutionary approach.

The tyrosyl-tRNA synthetases from Bacillus stearothermophilus (Bst-TyrTS) and Escherichia coli (Eco-TyrTS) are 56% identical in amino acid sequence. To map and characterize the set of interactions that makes Bst-TyrTS more stable than Eco-TyrTS, a family of nine hybrid proteins was constructed between the two enzymes. The N-terminal part of each hybrid came from Eco-TyrTS and the C-terminal part from Bst-TyrTS. The stability and activity of these hybrids were estimated by experiments of thermal inactivation and tRNA charging. For all the hybrids, the temperature of half-inactivation in 30 minutes was above 44 degrees C and the rate of charging was at least 40% that of Bst-TyrTS. In general, the temperature of half-inactivation increased and the rate of charging decreased monotonically when the number of residues coming from the more stable and less active Bst-TyrTS increased. As a result, the rate of charging decreased when the temperature of half-inactivation increased. These results show that the sequences and structures of the two enzymes can replace each other locally and still give a stable and active TyrTS, and that the greater stability of Bst-TyrTS is due to cumulative changes of residues scattered along the sequence. They suggest that Bst-TyrTS is more rigid than Eco-TyrTS at low temperature. The existence of a few exceptional hybrids, having stabilities or activities lower than those of the neighbouring hybrids, shows that compensatory changes of residues have occurred between the two sequences during evolution. These exceptions could be explained by the systematic identification of the couples of residues that are in contact in the Bst-TyrTS structure and become heterologous in some hybrids.

Binding Sites↗
PubMed1993

Nickel induces oscillatory behavior and enhanced synaptic and electrotonic transmission between stomatogastric neurons of Panulirus interruptus.

The pyloric pattern generator network of the stomatogastric ganglion uses a mixture of burst-inducing plateau potentials, synaptic transmission, and electrical coupling to produce its patterned output. This study examines the effects of two divalent, calcium channel blockers, nickel and cadmium, on voltage oscillations, synaptic transmission, and electrical coupling between the two pyloric dilator (PD) neurons and lateral pyloric (LP) neuron of Panulirus interruptus. The in vitro stomatogastric ganglion was bathed in saline containing tetrodotoxin (TTX) to eliminate Na-spikes and the spontaneous voltage oscillations of the pyloric rhythm, resulting in a steady resting potential. Addition of 50-100 microM Ni2+ to the TTX-saline induced voltage oscillations of similar amplitude and frequency as the endogenous rhythmic activity (before the application of TTX). 25-50 microM nickel enhanced graded synaptic transmission and electrical coupling and altered voltage waveforms, while producing little change in the input resistance measured in the soma. 10-1000 microM Cd2+ acted as a dose-dependent blocker of graded synaptic transmission, but had no other detectable effects. We propose that nickel, in contrast to cadmium, exerts a modulator-like effect deep in the pyloric neuropil.

Animals↗
PubMed1993

Histochemical and biochemical determination of calcium in salivary glands of cat.

Although feline salivary glands have been used in investigations on secretion and microlithiasis and both processes involved calcium, nothing is known about its distribution in these glands. Therefore we have demonstrated the presence of calcium by a histochemical technique using glyoxal bis(2-hydroxyanil) and a biochemical technique using dry ashing. The histochemical technique stained serous acinar cells weakly and rarely found mucous acinar cells strongly in the parotid gland, mucous acinar cells moderately to strongly and serous acinar cells weakly in the sublingual gland, and central and demilunar acinar cells moderately to strongly in the submandibular gland. The biochemical technique revealed less calcium in the parotid than in the submandibular and sublingual glands. Both techniques revealed a decrease of calcium in submandibular and sublingual glands following parasympathetic stimulation. The histochemical distribution of calcium, which corresponds to that of acinar secretory glycoprotein, and the loss of calcium following parasympathetic stimulation, which causes release of secretory granules, indicate the presence of calcium in secretory granules. The concentration of calcium in the different types of acinar cell corresponds to the acidity of the secretory glycoprotein and suggests that calcium is present as a cationic shield to allow the condensation of polyionic glycoprotein in secretory granules.

Animals↗
PubMed1993

Histochemical and biochemical determination of calcium in salivary glands with particular reference to chronic submandibular sialadenitis.

Although salivary calcification is relatively common, little is known about the localization and content of the calcium of normal and diseased human salivary glands. We investigated this in chronic submandibular sialadenitis with a variable mixture of relatively normal and extremely atrophic parenchyma and in normal submandibular, parotid and palatal glands. Calcium was localized histochemically in mucous acinar cells of submandibular and palatal glands at moderate to high levels, in serous acinar cells of submandibular and parotid glands at low to moderate or occasionally high levels, in mucous ductal cells at moderate to high levels, and in extremely atrophic parenchyma at low levels or not at all. Calcium was determined biochemically at relatively high levels in the different glands in the order palatal, submandibular, sialadenitis and parotid. However, the differences were small. The results indicate that most salivary calcium is associated with secretory granules; this is the likely source of the calcium involved in salivary calcification.

Calcium↗
PubMed1993

Histochemical and biochemical determination of calcium in pleomorphic adenoma.

Although calcification seldom occurs in pleomorphic adenoma, it often occurs in salivary glands, and so we decided to investigate the possible role of calcium in this difference. A histochemical method using glyoxal bis(2-hydroxyanil) demonstrated a small amount of calcium outlining lumina and separated cells of epithelial structures and associated with cells of myxoid and chondroid regions in pleomorphic adenoma, and a conspicuous amount in the acini of the associated salivary glands. A biochemical method using dry ashing demonstrated a significantly higher level of calcium in the glands than in pleomorphic adenoma. The results indicate that the calcium is mainly associated with secretory granules, which are scarce in pleomorphic adenoma, and with proteoglycan present intercellularly and in stromal regions of pleomorphic adenoma. The calcium in secretory granules is of possible importance in calcification in lumina and epithelium, and that bound to proteoglycan is possibly released following necrosis to be of importance in stromal calcification. However, the overall low level of calcium in pleomorphic adenoma is the likely explanation for the usual lack of calcification.

Adenoma, Pleomorphic↗
PubMed1993

The lymphoblast beta-adrenergic receptor in bipolar depressed patients: characterization and down-regulation.

beta-Adrenergic receptor binding and adenylyl cyclase activity were examined in lymphoblast cell lines established from 12 patients with bipolar disorder and 10 unrelated healthy control subjects. No significant differences were found in [125I]iodocyanopindolol binding affinity or capacity or in isoprenaline-stimulated cAMP response. Incubation of lymphoblasts with isoprenaline (1 nM) for 24 h prior to assay reduced both receptor number and adenylyl cyclase activity. The extent of receptor down-regulation was significantly less in cells of bipolar disorder patients (20 +/- 5%) compared to controls (40 +/- 4%). Desensitization of adenylyl cyclase, however, was reduced to a similar degree in bipolar (65 +/- 14%) and control (68 +/- 20%) subjects. We conclude that basal beta-adrenergic receptor characteristics are not altered in bipolar disorder but that agonist down-regulation of receptor number may be less efficient than in control cells. The functional implications of this effect are discussed.

Adenylyl Cyclases↗
PubMed1993

Successful control of hyperparathyroidism in patients on continuous ambulatory peritoneal dialysis using magnesium carbonate and calcium carbonate as phosphate binders.

To avoid the use of aluminium as a phosphate binder, patients on CAPD who were stable were dialysed against a peritoneal dialysis fluid which was magnesium free. A mixture of calcium and magnesium carbonate was used as a phosphate binder over a period in excess of 1 year. Vitamin D analogues were used in the majority. Results show satisfactory control of hyperparathyroidism with mean parathyroid hormone concentration for the group of 121 pg/ml (normal < 100 pg/ml), calcium concentration of 2.41 mmol/l, magnesium 0.97 mmol/l, phosphate 1.36 mmol/l and aluminium 0.35 mmol/l (normal < 0.2 mumol/l). These results were as good as and better in some respects than a minority using calcium carbonate alone or remaining on aluminium hydroxide, the latter remaining on Mg-containing CAPD fluid.

Calcium↗
PubMed1992

The treatment of sleep disorders.

Narcolepsy is clinically associated with cataplexy, sleep paralysis and hypnagogic hallucinations. It is treated by reassurance (that there is no physical disease) and by stimulants such as ephedrine and amphetamine on an intermittent basis. The special tricyclic antidepressant clomipramine is also used, and mono-amine oxidase inhibitors (MAOIs) are useful in theory. Obstructive sleep apnoea is an important and often unrecognised cause of daytime somnolence. It is treated by weight reduction (pickwickian syndrome), hormones, or recently, with continuous positive pressure apparatus. Night terrors (pavor nocturnus) and sleepwalking typically occur during deep sleep (stage 3 and 4 throughout the episode) in children. In a night terror the child sits up with a scream, with eyes open, but inaccessible. He eventually falls asleep calmly. Sleepwalking, too, shows the features of inaccessibility and subsequent amnesia for the episode. Both conditions are normally treated with reassurance (to the parents) but may occasionally warrant benzodiazepines. Enuresis usually occurs in non-rapid eye movement (NREM) sleep, especially stages 3 and 4. The reason for the efficacy of tricyclic antidepressants is not precisely known. Delirium tremens (DT) is treated as a rebound excess of REM sleep, with benzodiazepines and other drugs. It is the withdrawal syndrome (with or without major seizures) to the barbiturate-alcohol group of drugs, which includes alcohol, chloral, paraldehyde, glutethimide, methylprylone, ethchlorvynol, meprobamate and meprobamate-diphenhydramine. Insomnia may be treated by the above drugs, by analgesics, antidepressants, major tranquillisers (neuroleptics) and miscellaneous other compounds. For the majority of patients, however, the most suitable group seems to be the benzodiazepines. The benzodiazepines are much safer than their predecessors, in both acute and chronic usage.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Value of urinary copper excretion after penicillamine challenge in the diagnosis of Wilson's disease.

To investigate the diagnostic value of 24-hr urinary copper excretion testing after penicillamine challenge in the diagnosis of Wilson's disease, 75 consecutive children referred for a variety of liver problems and in whom parameters of copper metabolism had been investigated were analyzed retrospectively. Seventeen had Wilson's disease, 22 had autoimmune chronic active hepatitis, 6 had primary sclerosing cholangitis, 12 had chronic liver disease of various etiologies, 4 had cryptogenic acute liver failure, 6 had acute hepatitic illnesses and 8 had a variety of disorders featuring normal liver histological appearance. Serum ceruloplasmin and total copper levels were significantly lower in Wilson's disease patients compared with all other groups, but three children with Wilson's disease had normal ceruloplasmin levels and seven had normal total copper levels. No significant difference was found for free serum copper levels and liver copper content between Wilson's disease patients and the other groups. Baseline 24-hr urinary copper excretion was significantly higher in Wilson's disease patients compared with that of the other patients, but six children with Wilson's disease had levels just above the upper limit of normal, overlapping with values obtained in three children with liver failure, two with acute hepatitis, two with autoimmune chronic active hepatitis and three with primary sclerosing cholangitis. The 24-hr urinary copper excretion after penicillamine challenge proved the most accurate single diagnostic test; levels more than 25 mumol/24 hr were present in 15 of 17 patients with Wilson's disease, but in only 1 child with liver failure of the 58 with other disorders.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗