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Biomedical subjects

L Chan

Publications and source records attributed to L Chan.

At least 523 records · Page 29Linked to original sources
PubMed1975

Scoliosis: A prospective epidemiological study.

A two and a half-year prospective study was carried out to determine incidence rates and distributions of various parameters associated with idiopathic scoliosis. Data were also collected on the progression curves detected at the initial screening. The results showed: (1) that the incidence rate was 13.6 per cent with a female-to-male ratio of 1.2:1, (2) that the most common type of curve was thoracolumbar, and (3) that spontaneous improvement occurred in approximately 22 per cent of those patients followed for an average of one year.

Adolescent↗
PubMed1973

Rates of induction of specific translatable messenger RNAs for ovalbumin and avidin by steroid hormones.

In the chick oviduct, injections of estrogen and progesterone induce synthesis of the specific proteins ovalbumin and avidin, respectively. We have studied the rate of induction of the specific messenger RNA molecules for these proteins after a single injection of estrogen or progesterone. The mRNAs were extracted, partially purified, and quantified in vitro in a heterologous protein-synthesizing system. Single injections of estrogen in chicks previously withdrawn from all steroid hormones for 2 weeks led to rapid increases in ovalbumin mRNA with 3 hr, which coincided with increases in the rate of ovalbumin synthesis. Maximal ovalbumin mRNA activity occurred by 18-20 hr. The half-life of the mRNA was estimated to be 8-10 hr and corresponded to the half-life for cessation of intracellular ovalbumin synthesis after a single injection of an estrogen. Similarly, after an injection of progesterone into chicks first treated with estrogen, appearance of avidin mRNA preceded demonstrable accumulation of this specific protein in oviduct cells. The mRNA for avidin was first apparent at 6 hr, and reached maximal concentrations between 18 and 24 hr after injection. These data confirm that both estrogen and progesterone act on oviduct to induce rapid accumulation of specific mRNAs before and coincident with the appearance of the cell-specific induced proteins. The overall results of these experiments are compatible with the hypothesis that the production of mRNA is a rate-limiting step in the steroid hormone-mediated induction of protein synthesis.

Animals↗
PubMed1972

Mode of cell wall growth of Bacillus megaterium.

The growth of the cell wall of Bacillus megaterium KM was examined by labeling the cell wall uniformly with (3)H-alpha, epsilon-diaminopimelic acid and examining by radioautography the distribution of labeled cell wall material in daughter cells. The results indicate that the label is distributed uniformly to all daughter cells and rule out a single growth point, either central or apical, for these cells. The results strongly suggest that cell wall growth occurs by uniform deposition of new wall over the whole cell surface.

Autoradiography↗
PubMedDate not supplied

Neurocardiac toxicity of racemic D,L-lactate fluids.

Racemic D,L-lactate has long been used in burn therapy as Ringer's lactate and in peritoneal dialysis fluid for treatment of renal failure. The D-lactate component of this racemic mixture is known to cause two forms of neurological toxicity in patients: encephalopathy and, in a subset of the population, panic reaction. Here we demonstrate that coma, similar in degree to that produced by blood levels of 75 mM ethanol was induced in rats by the intraperitoneal infusion of sodium D-lactate sufficient to raise serum D-lactate concentration to 25 mM, whereas infusion of equal quantities of sodium L-lactate produced no observable neurological effect. We further demonstrate that the intravenous infusion of racemic D,L-lactic acid into 48-hour fasted rats produced serious disturbances of cardiac rate and rhythm leading to death. When serum D-lactate concentration had reached 1-2 mM there was bradycardia, at 2-3 mM prolongation of QT interval, at 6-7 mM AV block with ectopic escape rhythms, and at 11 mM death in ventricular standstill or fibrillation. In contrast, intravenous infusion of L-lactic acid to blood levels of 25 mM failed to produce any change in cardiac rhythm. On the other hand, the isolated working heart, free of influence from the central nervous system, displayed no change of cardiac rhythm or physiological function when perfused with 25 mM sodium D,L-lactate.

Adult↗
PubMedDate not supplied

Complications and nonclosure rates of fasciotomy for trauma and related risk factors.

The objective of this study was to identify risk factors for the development of complications and unsatisfactory skin closure following fasciotomy for trauma. Risk factors included in the study are prolonged time from injury to fasciotomy, type of fasciotomy, site of injury, and kind of underlying injury. The study was a retrospective analysis of 100 consecutive fasciotomies done for trauma over a period of 38 months (December 1991 to January 1995) in a "level I" trauma center at a university-affiliated county teaching hospital. Ninety-four patients were eligible for analysis, 29 of whom (31%) developed complications at the fasciotomy site. The risk was increased for lower extremity versus upper extremity (34.3% versus 20.8%), prophylactic versus therapeutic (42.0% versus 24.6%), late (>8 hours) versus early (37% versus 25%), and vascular versus musculoskeletal (38.8% versus 22.2%) trauma cases. The same risk factors negatively influenced the ability to close the skin primarily. The four subgroups defined by vascular/nonvascular injury and upper/lower extremity site had significantly different nonclosure rates (p = 0.043). The rate was highest among the vascular/lower extremity group (60.5%) and lowest among the nonvascular/upper extremity group (15.4%). We concluded that fasciotomies in lower extremities, the presence of underlying vascular injuries, fasciotomies performed prophylactically, and a time between the injury and fasciotomy of more than 8 hours are associated with an increased risk for local complications. The same factors are associated with an increased need for skin grafting the wound.

Adult↗
PubMedDate not supplied

Aggregation and predisposition to Ascaris lumbricoides and Trichuris trichiura at the familial level.

This study examines the persistence of familial aggregation and familial predisposition to Ascaris lumbricoides and Trichuris trichiura infection over 2 periods of treatment and reinfection, in an urban community in Kuala Lumpur, Malaysia. Both parasite species were shown to be aggregated (assessed by the variance to mean ratio) within families at all 3 interventions, although no consistent trend in aggregation was observed over the period of the study. Associations between mean A. lumbricoides and T. trichiura infection levels of families, at all 3 interventions, were highly significant (P < 0.0001), suggesting persistent predisposition at the family level.

Adolescent↗
PubMedDate not supplied

Pain comparison of unbuffered versus buffered lidocaine in local wound infiltration.

The purpose of this study was to compare the pain of infiltration between unbuffered lidocaine and buffered lidocaine in a traumatic laceration. Solutions of unbuffered 1% lidocaine and buffered 1% lidocaine were randomly assigned to Site I or Site II of a single laceration for each subject, with the patient serving as self-control. Pain scores were recorded for each site, and an anesthetic preference was determined for each patient. It was found that buffered lidocaine had a preference ratio of 3.0 over unbuffered lidocaine (95% confidence interval, 1.86 to 4.84; P less than 0.0001). It was also found that Site I was preferred more often than Site II regardless of which medication was used. The conclusion is that buffered lidocaine is preferred over unbuffered lidocaine and that the order of injection is an important factor in trials that involve multiple sequential injections in the same patient.

Adult↗
PubMedDate not supplied

An unusual presentation of cat scratch encephalitis.

Cat scratch disease is an infectious illness that has been recognized since the 1880s; however, our understanding and knowledge of it is still evolving (1). It was not until 1991 that the etiologic species, Rochalimaea, was finally confirmed (2,3). Only recently have the breadth of its clinical spectrum and the population at risk been appreciated. We now realize that signs and symptoms that had been considered cardinal for diagnosis may be absent. Cat scratch disease was known to afflict primarily children and adolescent; however, the incidence of CSD is increasing in immunocompromised groups, such as AIDS and transplant patients (3,4). The recent discovery of the infectious agent and improved understanding of the disease process have led to new approaches in diagnosis and treatment. We present a report of a patient with cat scratch disease who presented with seizure and altered mental status secondary to encephalitis.

Bartonella henselae↗