Assessment of skin types, skin colours and cutaneous responses to ultraviolet radiation in an Asian population.

Ninety normal individuals were included in this study on skin types, skin colours and cutaneous responses to ultraviolet radiation. Skin types were recorded using Fitzpatrick's classification, skin colours were measured using the Minolta Chromameter CR-300, and cutaneous responses to UV radiation were measured in terms of minimal erythema dose (MED) to UVA, UVB and the immediate pigment darkening dose to UVA (IPDDA). Skin colour measurements were taken from the right cheek to represent facultative skin colours, and from the buttock to represent constitutive skin colours. The colours measured were expressed by the L x a x b colour space. Skin types and some colour parameters (L and b from covered parts of body) correlated fairly well with the minimal erythema doses (MED) to UVA and UVB. Skin colour measurements are more objective than skin type assessment and could be better markers of photosensitivity. However, there is still considerable overlap in MEDs for persons with different skin colours, and further studies of these parameters are warranted. Our MEDs are higher than other reports on similar skin types and skin colours. This could be due to differences in methodology, genetic make-up or acclimatization from chronic sun exposure. This illustrates the importance of local controls for each institution dealing with photosensitive disorders.

Relationship of the renin-angiotensin system and systemic arterial pressure to sodium excretion during atrial natriuretic peptide infusion in men.

The goal of this study was to evaluate the relative contribution of the renin-angiotensin system and mean arterial pressure to sodium excretion and urine flow rate during an infusion of atrial natriuretic peptide (ANP) at physiologically relevant doses in humans. Eight normal volunteers were studied during five periods: (1) baseline in the supine position; (2) during an infusion of ANP at physiologic doses (0.01 micrograms/kg/min) in the supine position; (3) during ANP infusion and 60 degrees head-up tilt; (4) during ANP infusion, head-up tilt, and interruption of the renin-angiotensin axis with the angiotensin converting enzyme inhibitor (ACEI) enalaprilat; and (5) in the supine position during ANP infusion and ACEI. Infusion of ANP in the supine posture significantly increased urine flow rate and sodium excretion compared to baseline while mean arterial pressure and plasma renin activity were unchanged. During head-up tilt and ANP infusion, urine flow rate and sodium excretion were no longer significantly elevated over baseline while mean arterial pressure decreased and plasma angiotensin II levels increased. Addition of ACEI caused a marked diminution of urine flow rate and sodium excretion compared to baseline levels despite continued ANP infusion. Although mean arterial pressure after ACEI administration was lower than baseline, it was not significantly different from the non-ACEI head-up tilt state. Placing subjects in the supine position during ANP infusion and ACEI administration increased mean arterial pressure to levels that were no longer different from baseline, but urine flow rate and sodium excretion remained significantly depressed to the same degree as during head-up tilt with ACEI.(ABSTRACT TRUNCATED AT 250 WORDS)

Vestibular toxicity due to gentamicin in peritoneal dialysis patients.

Gentamicin is well known to be a cause of vestibular toxicity. Despite this, gentamicin is often used to treat peritonitis and exit-site infections in peritoneal dialysis patients because of the ease of intraperitoneal administration and the broad coverage of aerobic Gram-negative bacilli, including Pseudomonas aeruginosa. We report 4 cases of severe vestibular toxicity occurring in peritoneal dialysis patients treated with gentamicin. They were all treated as outpatients for peritonitis or an exit-site infection while on continuous ambulatory peritoneal dialysis (CAPD) or continuous cyclic peritoneal dialysis (CCPD). The drug was administered to 3 patients in each peritoneal exchange (5 mg/L) after a loading dose. A fourth patient was given 1 mg/kg of intraperitoneal gentamicin every other day. The mean length of treatment was 21 days. Levels were not used to adjust the doses. All developed severe vertigo from which there was incomplete or no recovery. We suggest that gentamicin and the other aminoglycosides should be used in peritoneal dialysis patients only when there is no suitable alternative antibiotic. When gentamicin is administered, levels should be carefully followed. Studies should be performed in peritoneal dialysis patients on the feasibility of dosing gentamicin intermittently, which may be less toxic than continuous intraperitoneal administration.

Acid excretion and serum electrolyte patterns in patients with advanced chronic renal failure.

Hyperchloremic metabolic acidosis can be seen in advanced chronic renal failure (CRF). To study this further, we measured acid excretion under controlled conditions in 19 patients with severe but stable CRF. Twelve patients had a hyperchloremic metabolite acidosis, 3 had an elevated anion gap acidosis ('delta acidosis'), while the 4 remaining patients had a slightly decreased tCO2 with a normal anion gap and serum chloride level ('mild acidosis'). Ammonium excretion was markedly reduced in CRF patients (11 +/- 1 vs. 32 +/- 2 mEq/day in normal subjects, p less than 0.005), and likewise urinary titratable acid was diminished (18 +/- 2 mEq/day in patients, vs. 28 +/- 3 mEq/day in normal subjects; p less than 0.005). When expressed per 100 ml GFR, ammonium and titratable acid excretion were markedly increased in all groups of patients compared to normal subjects. The Tm for bicarbonate was 22.5 +/- 3.7 mEq/l for all CRF patients and 24 +/- 1 mEq/l for the patients with a hyperchloremic metabolic acidosis. We conclude that the hyperchloremic metabolic acidosis in advanced renal failure is due to diminished excretion of ammonium and titratable acid and is not due to an increased bicarbonate leak. As renal failure advances and renal mass declines, the remaining functioning nephrons hypersecrete acid.

Gram-negative arthritis with a simultaneous urinary tract infection in a renal transplant recipient.

Infections are common causes of morbidity in the renal transplant population, but infectious arthritis is rarely encountered. Gram-negative joint infections in the nontransplant population are often associated with simultaneous urinary tract infections. We report a case of Escherichia coli monoarthritis and a concomitant urinary tract infection in a renal transplant recipient and consider the possible predisposing factors for the infection.