PubMed HealthSearch

Biomedical subjects

H A Johnson

Publications and source records attributed to H A Johnson.

At least 19 recordsLinked to original sources

Diminishing returns on the road to diagnostic certainty.

In the quest for diagnostic certainty, one can be led into a false sense of accomplishment by the results of sensitive, specific, and well-executed diagnostic tests that provide little or no diagnostic information. This is a consequence of the fact that as one approaches diagnostic certainty the useful information returned by diagnostic tests and observations approaches zero. This can be demonstrated by calculating the quantity of useful information provided by a test in a given clinical environment as one approaches certainty of diagnosis.

Cost-Benefit Analysis

Massive splenomegaly.

A 16 year review of 391 splenectomies performed at New England Medical Center was done to evaluate the morbidity and mortality of patients with drained splenic weights greater than 1,000 grams. Thirty-six met the criteria for study. Twenty men and 16 women with an average age of 55.4 years were identified. Myeloproliferative disorders were the most predominant cause of massive splenomegaly. Pancytopenia and hemolytic complications of the disease processes were the most acute indications for operations. The average time between diagnosis and operative intervention was 42 months. An average of 10 units of blood products were required to correct preoperative coagulopathy. Eleven of 36 patients had postoperative complications. Eight of 21 with drains and an equal number of patients with preliminary splenic arterial ligation had complications. Eight-one per cent of all complications were infection related. Complication increased the length of stay 11 days. The 30 day mortality rate was 11.1 per cent. Sepsis was the major cause of mortality. Closed drainage system provided no demonstrable benefit nor appeared to be the cause of sepsis. No episodes of pulmonary embolic phenomenon or peripheral venous thrombosis were demonstrated. Elective splenectomy in patients with smaller spleens was performed without operative mortality and with 3 per cent morbidity rate. For patients with massive splenomegaly, the average survival time was 28.5 months. The majority of these patients died from complications of the disease. Preoperative coagulopathy, failure to demonstrate a hematologic response to splenectomy and reoperation were clear predictors for decreased long term survival periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent

The influence of thiamine deficiency and ethanol on rat brain catecholamines.

In rats treated with a thiamine deficient diet for 30 days the brain content of total thiamine decreased by 27-50%. Thiamine deficiency decreased the dopamine (DA) concentration of the striatum indicating a reduced synthesis of DA. In the hypothalamus the levels of the catecholamine metabolites homovanillic acid (HVA) and 4-hydroxy-3-methoxyphenyl glycol (HMPG) were reduced indicating a reduced DA and noradrenaline (NA) turnover. Animals on a diet containing 5% ethanol had increased concentrations of HVA and HMPG in rest brain indicating an increased DA and NA turnover. The concentration of 1-carboxysalsolinol (1-CSAL) and salsolinol (SAL) in the brain stem was increased in animals receiving ethanol. Thus, both thiamine deficiency and ethanol treatment influenced the catecholamine system in a complex region-dependent way. In the brain regions most susceptible to brain damage in thiamine deficiency, i.e., hypothalamus and brain stem, 1-CSAL and SAL increased most following thiamine deficiency combined with ethanol intake.

Alcohol Drinking

Thermal noise and biological information.

Thermal noise limits the efficiency of all information-handling systems. This principle, which is a routine consideration in electronics, is just as fundamental to the handling of highly specific information by living organisms. The rapid basal turnover rates of cells and intracellular proteins and the high energy consumption of regulatory organs, previously unaccounted for, can be explained to a large extent by the need to compensate for the steady loss of essential information due to thermal noise.

Aging

On quality of life.

Explore the source record for details and available documents.

Attitude to Health

Burkitt's lymphoma with ileocecal and subdiaphragmatic masses.

Approximately 25 new cases of American Burkitt's lymphoma (ABL) are diagnosed and reported yearly. Black patients presenting with ABL occur in less than 5 percent of the reported cases. A 47-year-old black man with ABL and ileocecal masses typical of the disease is presented. Symptoms, physical findings, and radiologic features of the disease are assessed. The combined modality of aggressive surgical extirpation and chemotherapy may improve remission and survival time by reduction of tumor burden.

Burkitt Lymphoma