Folate-homocysteine interrelations: potential new markers of folate status.

We report a transient drop in plasma Hcy and Cys following a single oral dose of PteGlu. The thiol change was concomitant with both the peak plasma 5CH3H4PteGlu1 level (by HPLC) and the maximum plasma Lactobacillus casei activity which reflects absorption of unmodified PteGlu. The significant reciprocal association of Hcy with radioassay RBC folate (r = -0.28, 99% CI -0.48, -0.05, P = 0.0016), serum folate (r = -0.37, 99% CI -0.56, -16, P = 0.0001), and vitamin B12 (r = -0.42, 99% CI -0.59, -21, P = 0.0001) is shown and reflects the long-term nutritional effect of B vitamins on this important, potentially atherogenic thiol. These are now well-established associations. We extend the potential for investigation of folate metabolism in health and disease by evaluating a range of new folate indices which are based on erythrocyte coenzymes. These have been looked at independently and in association with established parameters. Erythrocyte methylfolates (mono- to hexaglutamate-5CH3H4PteGlu1-6), formylfolates (tri- to pentaglutamate-5CHOH4PteGlu3-5),formiminotetrahydrofolate (formiminoH4PteGlu1), unsubstituted tetrahydrofolate (H4PteGlu1), andpara-aminobenzoylglutamate (P-ABG) have been measured by HPLC with fluorescence detection. A positive linear association exists between (i) H4PteGlu1 and radioassay RBC folate (r = 0.50, 99% CI 0. 07, 0.77, P = 0.0036), and (ii) H4PteGlu1 and tetraglutamates of both formyl- and methylfolate (r = 0.52, 99% CI 0.10, 0.78, P = 0. 0022, and r = 0.56, 99% CI 0.15, 0.80, P = 0.0009, respectively). Since, in addition, a reciprocal linear association exists between Hcy and tetraglutamyl formylfolate (r = -0.41, 99% CI -0.73, 0.05, P = 0.0206), erythrocyte tetraglutamates may be a good reflection of the bodies' active coenzyme pools. Pentaglutamyl formylfolate, the longest oligo-gamma-glutamyl chain form of this coenzyme may be a good indicator of folate depletion. The abundance of this coenzyme both increases with increasing Hcy (r = 0.55, 99% CI 0.13, 0.80, P = 0.0014) and increases as H4PteGlu1, the principle folate congener, decreases (r = -0.59, 99% CI -0.82, -0.20, P = 0.0004). Furthermore, the apparent equilibrium between substrate (5CH3H4PteGlu1) and product (H4PteGlu1) of methionine synthase is significantly associated with the abundance of 5CHOH4PteGlu5 (r = -0.53, 99% CI -0. 79, -0.11, P = 0.0018). This suggests that low methionine synthase activity for whatever reason (metabolic or dietary) may lead to an increase in the relative abundance of 5CHOH4PteGlu5. Like 5CHOH4PteGlu5, evidence is given that 5CH3H4PteGlu6, the longest oligo-gamma-glutamyl chain form of this particular coenzyme pool, may also be a good indicator of folate depletion. This is shown by a change in the relative proportion of erythrocyte methylfolate polyglutamates following supplementation with 400 microg/day PteGlu. Short-chain polyglutamates of methylfolate (5CH3H4PteGlu1--> 5CH3H4PteGlu4) increase in proportion to the total methylfolate pool, while long-chain polyglutamates of methylfolate (5CH3H4PteGlu5 and particularly 5CH3H4PteGlu6) decrease in their relative abundance.

Plasma vasopressin and response to treatment in primary nocturnal enuresis.

AIMS: To examine the relation between nocturnal vasopressin release and response to treatment with the vasopressin analogue 1-desamino-8-D-arginine vasopressin (DDAVP) in children with primary monosymptomatic nocturnal enuresis. DESIGN: Children were recruited from a specific enuresis clinic and entered into a defined treatment programme. Nocturnal vasopressin concentrations were measured every 15 minutes over a four hour period during overnight admission. RESULTS: Sixty seven children were eligible for entry into the study, 35 of whom agreed to overnight sampling. There was a quadratic relation between mean plasma AVP and response to treatment with DDAVP, with very high or very low concentrations being unresponsive. Plasma AVP profiles ranged from low concentrations with little variability to high concentrations with wide variability. CONCLUSION: The ability to respond to DDAVP is related to endogenous AVP production and is influenced by neuronal patterning in early infancy. The best predictors of success with treatment were a past history of breast feeding, mean nocturnal AVP concentration, and the height of the child. The response was adversely affected by poor weight at birth and poor linear growth. The study suggests differing causes of nocturnal enuresis related to different patterns of AVP release.

Adjudicating ventilator-associated pneumonia in a randomized trial of critically ill patients.

PURPOSE: The purpose of this study was to evaluate an adjudication strategy for diagnosing ventilator-associated pneumonia (VAP) in a randomized trial. MATERIALS AND METHODS: In a double-blind trial of sucralfate versus ranitidine, one of four pairs of adjudicators examined each case of clinically suspected VAP. Nurse and physician notes and all relevant laboratory data were allocated to each adjudication pair in groups of five patients. Each reader in the pair decided whether the patient had VAP; differences were resolved by consensus discussion. RESULTS: The overall unadjusted study odds ratio for VAP was 0.82 (P = .21) representing a trend toward less pneumonia with sucralfate compared with ranitidine. The odds ratio adjusted for adjudication pair was 0.85 (P = .27). The proportion of charts adjudicated as VAP positive among pairs ranged from 50% to 92%; crude agreement between readers in each pair varied from 50% to 82%. When adjudicators disagreed, the final consensus was split evenly between the two adjudicators' initial opinions in two pairs; in the other two pairs, the final decision reflected one dominant initial opinion. Personnel time to adjudicate all patients with a suspicion of VAP was 74 days. CONCLUSIONS: Though adjudication of outcomes such as VAP is time-consuming, consistent decision-making requires strict criteria, training, and calibration. Patients should be assigned to adjudication teams through random allocation.

The responsiveness of plasma homocysteine to small increases in dietary folic acid: a primary care study.

OBJECTIVES: To assess the long term effects of small increases in dietary folic acid on the concentration of plasma homocysteine, an independent risk factor for occlusive vascular disease, in a general population. DESIGN: A randomized double-blind placebo-controlled intervention study. SUBJECTS: One hundred and nineteen healthy volunteers, whose intake of fortified or supplemental folic acid was low, were recruited by letter from the patient register of a large inner-city group general practice. METHODS: Volunteers were randomized to receive unfortified cereals, or cereals fortified with 200 microg of folic acid per portion, with or without other vitamins. Blood samples were taken presupplement and at 4, 8 and 24 weeks on treatment and analysed for plasma homocysteine, cysteine and vitamin B12 and serum and red cell folate. Ninety-four subjects completed the study providing blood samples on all four occasions. RESULTS: There were no significant changes in any measured parameter in those eating unfortified cereals. Overall, folic acid fortification of cereals led to significant increases (P < 0.001) in serum folate (66%), and red cell folate (24%), and a decrease in plasma homocysteine (10%; P < 0.001). There were no changes in vitamin B12 or cysteine. The homocysteine decrease persisted until the end of the study and was primarily seen in those who initially had the highest plasma homocysteine or the lowest serum folate. CONCLUSIONS: If homocysteine is found to be a causative risk factor in occlusive vascular disease, food fortification with physiological levels of folic acid should have a significant impact on the prevalence of the disease in the general population.

The effectiveness of desmopressin in the treatment of childhood nocturnal enuresis: predicting response using pretreatment variables.

OBJECTIVE: To determine the factors that predict the effectiveness of desmopressin in the treatment of childhood nocturnal enuresis. PATIENTS AND METHOD: Sixty-six children with monosymptomatic nocturnal enuresis were treated with intranasal or oral desmopressin for a 4-week period. starting with a standard dose of 20 microg (0.2 mg oral) and increasing after 2 weeks where no progress was apparent to 40 microg (0.4 mg oral). Before treatment a range of variables (demographic, situational, enuretic history, physiological, parental attitude and child) were recorded. Three parameters of success acted as dependent variables, with stepwise linear regression models used to determine pretreatment predictors of success with desmopressin. RESULT: Each outcome variable produced a very similar model of predictors. Success, as assessed by the most dry nights over a 14-night period, was associated with less severe enuresis before treatment, a parental belief that the child's enuresis was unstable and higher birthweight. CONCLUSION: From the analysis, a model of arginine vasopressin release is proposed and the clinical implications of the findings addressed.

Hemodynamic and pathologic effects of prostacyclin on oleic acid-induced pulmonary injury.

Oleic acid (OA) injection into the lungs of dogs produces pulmonary edema and decreased cardiac output, and the result is combined hypoxic and stagnant hypoxia. Prostacyclin (PGI2) has some effects that may be beneficial in the alleviation of hypoxia. We studied 18 anesthetized dogs that were divided into three groups: (1) Six dogs acted as controls and did not receive OA or PGI2, (2) six dogs received OA but no PGI2, and (3) six dogs were first given OA and 1 hour later an infusion of PGI2 (100 ng/kg/min) was started and continued for 4 hours. All dogs were killed at the end of the study and their lungs were removed for weighing and preparation for microscopic examination. Compared with controls, OA caused a low cardiac output, high systemic and pulmonary vascular resistance, and increased right-to-left intrapulmonary shunt. The group that received OA and PGI2 demonstrated a well-maintained cardiac output and a low systemic vascular resistance. Right-to-left intrapulmonary shunt, however, increased in these dogs compared with the dogs not given PGI2. All animals given OA had similar wet/dry lung weights and histologic appearances. Our results suggest that the only beneficial effect of PGI2 in OA-induced lung injury is to improve the stagnant hypoxia, but this is associated with an aggravation of the hypoxic hypoxia. The result of these competing effects appears to be a mild overall improvement in oxygen delivery as suggested by the slightly higher mixed venous PO2 in the group that received PGI2.

Isoquinoline is a possible anti-psoriatic agent in coal tar.

Isoquinoline has been identified as a component of coal tar which causes interfollicular regions of parakeratotic stratum corneum in mouse tail epidermis to become orthokeratotic, with concomitant production of a granular layer. In this respect it behaves similarly to coal tar itself, and isoquinoline may contribute to the anti-psoriatic activity of coal tar.

An alternative pharmacological approach to the detection of anti-androgenic drugs for acne therapy.

Both testosterone and dihydrotestosterone may be able to stimulate sebaceous glands, and the glandular function may continue under direct testosterone control in the presence of 5 alpha-reductase blockade. Antagonism of sebaceous gland hypertrophy, induced by exogenous testosterone or dihydrotestosterone, has been studied in the hairless hamster using established and experimental drugs applied topically. The results support the proposition that testosterone plays a direct role in mediating sebaceous gland response. This suggests possibilities for the design of sebum inhibitory drugs with minimal systemic anti-androgenic side effects.

Inhibition of dihydrotestosterone-mediated hamster sebaceous gland hypertrophy by progesterone.

In the hairless hamster, progesterone can antagonize dihydrotestosterone-mediated hypertrophy of the sebaceous gland.

A quantitative approach to epidermal wound healing: the effect of dexamethasone on regenerating epithelium.

The effect of dexamethasone on the regeneration of new epithelium over the base of an excised suction blister has been studied over a period of 9 days. It was found that dexamethasone did not significantly affect the migration of epidermis over the blister base but it did significantly reduce the number of cells in DNA synthesis and post wounding acanthosis of wound edge and regenerating epithelium.

Practical applications of the Quantimet 720, an image analysing computer, in the field of investigative dermatology.

Image analysing computers can perform quantitative measurements of epidermal thickness, sebaceous gland volume, and labelling indices of epidermis easily, rapidly and automatically. All these parameters are extremely important in investigative dermatology and this paper describes how they are measured using the Quantimet 720.