Kinetics of reduction of the primary donor of photosystem II. Influence of pH in various preparations

The kinetics of reduction of P-680, oxidized by a flash, have been measured with chloroplasts treated with Tris, hydroxylamine or cholate, with PS-II particles from Phormidium (Tris-treated) and with subchloroplast particles prepared with digitonin or Triton. In all cases the electron transfer from D1 to P-680+ has similar rates, influenced similarly by pH and D1 has a one-electron capacity.

Quick prediction of creatinine clearance without the necessity of urine collection

The Cockcroft-Gault formula enables a rapid prediction of the creatinine clearance (CCr) to be made without having to collect urine and using the variables of plasma creatinine, body weight, sex and age. The formula was used to predict the CCr in 100 consecutive patients and comparisons made with the measured CCr and the 51chromium EDTA clearance. The advantages of being able to quickly predict the creatinine clearance using this formula are discussed.

A simple and reliable method for calcium balance using combined period and continuous fecal markers

Calcium balances were determined in 13 patients during 2--4 3-day periods following both period marking (with carmine) and continuous marking (with polyethylene glycol or chromium). The reliability coefficient for the uncorrected fecal calcium (obtained from period marking) from one period to another was 0.82, whereas it was 0.97 for corrected fecal calcium (determined from recovery of continuous marker in 3-day fecal pools). Thus, the addition of continuous marking yielded a significantly more reliable measure of fecal calcium than obtainable by the use of period marking alone (p < 0.05); the error variance for corrected fecal calcium from one period to another was 3%, whereas it was 18% for uncorrected fecal calcium. It is concluded that a reliable measure of fecal calcium, and hence calcium balance, could be obtained by combined use of continuous and period markers, involving fecal collection over only one 3-day study period (marked by period marker), and correction of fecal calcium for the completeness of fecal collection (determined from continuous fecal marker).

Absence of significant antiviral effects of beta-gamma-methylene GTP on encephalomyocarditis virus infection of L cells and mice

The protein synthesis inhibitor beta-gamma-methylene guanosine triphosphate (Gpp-CH2p) is shown here to be ineffective as a 'leaky membrane' antiviral agent against encephalomyocarditis virus infection of L cells and mice. Studies with GppCH2p in encephalomyocarditis virus-infected L cells indicate that the cells only become permeable to the inhibitor late in infection because the compound significantly inhibits protein synthesis only when added at 4 h p.i. At this time 50 to 70% of the new infectious virus particles have already been synthesized, and this is reflected in maximum inhibition of virus yields of only about 40%. Moreover, comparison of inhibition of protein synthesis by GppCH2p in vitro and in cell cultures indicates that the intracellular concentration attained is only 0.25% of that in the medium. The lack of antiviral activity of GppCH2p in encephalomyocarditis virus-infected mice is probably due to leakiness of infected cells occurring too late for sufficient inhibition of virus synthesis to be obtained.

Hearing loss in very low birthweight infants treated with neonatal intensive care

The hearing of 111 perinatal intensive care survivors of birthweights 1500 g or less was assessed at a mean age of 6 1/2 years (range 4--12). These 111 infants included 86% of the long-term survivors of this birthweight cared for in the newborn unit of University College Hospital, London, during the years 1966--72. All these infants were nursed in commercially available incubators for periods ranging from 2 to 80 days (mean 37) in which the mean noise threshold was 65 dB. Ten (9%) had sensory neural nearing losses, one (1%) infant had a congenital conductive hearing loss, and 21 (19%) infants had exudative otitis media with a mean loss of 25 dB. Apnoeic attacks in the neotal period were the most significant predictors of hearing loss in these infants (P less than 0.05) and an indirect serum filirubin level of at least 170 micromol/l (10 mg/100 ml) in the neonatal period had an additive effect (P less than 0.05). There was no evidence that ambient noise had affected the hearing of these very low birthweight infants.

XO/XY mosaicism and non-fluorescing Y chromosome in a male

An adult male of short stature and with underdeveloped external genitalia is described, who carried out a number of sexual assaults on young women. He proved to have XO/XY mosaicism and a non-fluorescing Y chromosome. It was considered to be a terminal deletion on morphological grounds. It is suggested, on the evidence of the small number of XO/XY mosaics examined by appropriate staining methods, that an abnormal Y chromosome, whether terminally deleted or non-fluorescing owing to an altered chemical state, predisposes to anaphase lagging and non-disjunction. Of eleven reported cases of XO/XY mosaicism with a non-fluorescing Y chromosome, this is the fifth of male phenotype. The severe behaviour disturbance of early onset is considered to be probably causally associated with the chromosome anomaly.

The influence of enzymatic cleavage and chemical modification of human and rabbit IgG on their reactivity with staphylococcal protein A

Proteolytic cleavage fragments from rabbit IgG have been isolated and characterized in an attempt to locate the sites involved in the reactivity with Staphylococcal protein A. The plasmin cleavage product Facb together with the pepsin cleavage products F(ab')2 and pFc' failed to react in contrast to the papain Fc fragment. These data, together with data from unfractionated plasmin digests, in which the Facb fragment remains associated with the plasmin pFc' fragment, indicate that inter-domain interactions are important in the maintenance of this activity. beta2-microglobulin was also shown to be unreactive with protein A. Chemical modification studies employing flurescamine, tetranitromethane and potassium cyanate indicate that lysine and tyrosine residues are not involved in the reactivity of human and rabbit IgG with protein A.

Enhancement of renal excretion of uric acid during long-term thiazide therapy

The effect of thiazide (hydrochlorothiazide 100 mg per day orally in two divided doses for up to 3 years) on uric acid metabolism was examined in 21 patients with renal stones suffering from renal hypercalciuria or absorptive hypercalciuria. Serum concentration of uric acid increased during thiazide therapy in every patient. In 12 of 21 patients, there was a transient or persistent rise in urinary uric acid of more than 50 mg per day during treatment. The mean urinary uric acid produced by thiazide was positively correlated with the change in the renal clearance of uric acid. Thus, an increase in urinary uric acid was often associated with a rise in uric acid clearance. The results suggest that thiazide may either increase the production of uric acid or decrease the extrarenal disposal of uric acid, in some patients.

The meaning of health: understanding functional limitations

Results of psychometric studies of 14 questionnaire items commonly used to define chronic functional limitations due to poor health are reported. Self-administered questionnaires were used to gather data from 1,209 persons 14 years of age and older. Data were used to study: scalability of items; test-retest reliability of alternate forms of scales; validity of scales in relation to 13 health status variables and age; and precision of scales in detecting differences in health. Three scales pertaining to chronic limitations in mobility, physical activity, and social role activity functions satisfied the criteria of scalogram analysis. Four-month test-retest reliability estimates for alternate forms were very high. Strong associations (some curvilinear) were observed among functional limitation scales, and between these scales and survey measures of physical abilities, general health perceptions, health worry/concern, chronic disease conditions, and age. Measures of physical abilities and functional limitations appeared to define opposite ends of a function-dysfunction continuum. Statistical modeling of precision indicates that, due to the skewed distribution of scores, large sample sizes would be required to detect differences in functional limitations in studies using only a posttest.

Cardiac arrest due to hyperkalemia following therapy for acute lymphoblastic leukemia

A patient with acute lymphoblastic leukemia with a large tumor burden is presented. Following successful chemotherapy, the patient experienced a cardiac arrest presumably due to hyperkalemia in association with hyperuricemia. The implication of these findings for patients with responsive hematological malignancies is discussed.