VITAMIN D NUTRITION AND VITAMIN D METABOLISM IN THE PREMATURE HUMAN NEONATE

The effect of supplementation with daily doses of vitamin D2 (1000 IU or 3000 IU, 25-75 micrograms, 63-189 nmol) has been studied in 39 premature neonates, initial gestational age 25-32 weeks. The initial mean plasma 25-hydroxyvitamin D was 25.8 nmol/l (10.3 ng/ml) but in 12 infants, most of whom were born in the winter months, the level was less than 15 nmol/l (6 ng/ml), and in seven babies plasma 1,25-dihydroxyvitamin D was less than 48 pmol/l (20 pg/ml). These findings suggest a considerable degree of maternal vitamin D-deficiency. Maximum attained concentrations of 25-hydroxyvitamin D on treatment were 77.3 nmol/l (30.9 ng/ml), high dose and 86.8 nmol/l (34.7 ng/ml), low dose, the mean rate of increase was greatest during the first two weeks (2.2 nmol/l/d; 0.88 ng/ml/d) and declined over the next 4 weeks. Mean maximum concentrations of 1,25-dihydroxyvitamin D2 were 283 pmol/l, (121 pg/ml), high dose and 309 pmol/l (129 pg/ml), low dose. Apart from a minor contribution to the initial plasma 1,25-dihydroxyvitamin D concentration, no effect of gestational age could be discerned in any of the measured variables. The endogenous pool of 1,25-dihydroxyvitamin D3 decayed with a T 1/2 of 22.5 d, indicating that vitamin D supplementation of these infants was necessary to avoid vitamin D-deficiency.     

Fine Structural Alterations Induced in Platelets by Adenosine Diphosphate

Blood platelets exposed to the nucleotide adenosine diphosphate (ADP)lose their discoid appearance and adhere to one another. The basis for theADP induced shape change has remained obscure. In the present study thestructural transformations of platelets under the influence of ADP have beenexamined in the electron microscope. Loss of lentiform appearance is closelyrelated to a marked reorganization of the platelet hyaloplasm. The marginalbundle of microtubules decreases in circumference and is moved into theinterior of the platelet. Granules and other organelles are transported to thecell center where they are enveloped within a web of microtubules and microfilaments. These changes are completely reversed after the influence of ADPdisappears. The movement of the circumferential bundle of microtubulesfrom its position under the cell wall appears to be the principle cause forthe loss of discoid shape. Constriction of hyaloplasmic elements followed bycomplete recovery of unaltered appearance are indicative of a reversible waveof contraction occurring in the platelet hyaloplasm. Thus the change in plateletsurface contour after exposure to ADP is not due to a direct modification ofthe cell wall by ADP, but to a contractile wave which ADP indirectly triggers in the substance of the cells.

Submitted on March 28, 1967 Accepted on November 1, 1967     

A Case Series: Herpes Simplex Virus as an Occupational Hazard

ABSTRACT

Statement of the Problem: Herpes labialis infections are common and present a serious risk to the dental team. Purpose of the Study: The purpose is to make dentists aware of the risks involved with treatment of patients with active herpes labialis. In addition, evidence‐based risk‐management strategies are presented. Methods and Materials: The incidence and natural history of herpes simplex virus type 1 (HSV‐1) are reviewed. Four previously unreported case histories are presented to illustrate the impact common sequelae of HSV‐1 can have on the dental team. The differences between HSV‐1 and the blood‐borne diseases which are the focus of universal precautions are discussed. In particular, the highly contagious, highly transmissible nature of HSV‐1 and its transmission through aerosols are highlighted. Finally, the need to include protection against aerosols in the profession's understanding of universal precautions is noted. Results: The authors suggest limiting the treatment of patients with active lesions to urgent care only, and treating active HSV‐1 lesions to reduce time of healing. For four common clinical situations involving HSV‐1 infections, evidence‐based methods for protecting the dental team and the patient from cross‐contamination are also presented. Conclusion: While it is clear that the treatment of patients with active herpes labialis lesions increases risk of cross‐infection, there are good protocols for controlling this risk.

CLINICAL SIGNIFICANCE

By bringing common vectors of cross‐infection to light and providing evidence‐based protocols for preventing them, this article provides practitioners with positive steps that can be taken for controlling the risk of spreading herpes infections to the dental team. (J Esthet Restor Dent 24:61–67, 2012)     

AA genotype of IL‐8 −251A/T is associated with low PaO2/FiO2 in critically ill patients and with increased IL‐8 expression

Background and Objective: Interleukin‐8 (IL‐8) is a central chemokine in acute respiratory distress syndrome (ARDS), and the IL‐8 gene contains a functional single nucleotide polymorphism (SNP) ?251A/T in its promoter region. We hypothesized that IL‐8 ?251A/T SNP is associated with PaO₂/FiO₂ in critically ill patients. Methods: We conducted genetic‐association studies in intensive care units at academic teaching centres using a derivation septic shock cohort (vasopressin and septic shock trial (VASST), n = 467) and a validation post‐cardiopulmonary bypass surgery cohort (CPB, n = 739) of Caucasian patients. Patients in both cohorts were genotyped for IL‐8 ?251A/T. The primary outcome variable in both cohorts was the fraction of patients who had a PaO₂/FiO₂ < 200. IL‐8 mRNA expression was measured in genotyped lymphoblastoid cells in vitro. Results: The frequency of the patients with PaO₂/FiO₂ <200 was significantly greater in patients who had the AA genotype of ?251A/T than in patients who had the AT or TT genotypes in both VASST (AA = 60.8% vs AT and TT = 53.8% and 48.0%, P = 0.038) and the CPB cohort (AA = 37.0% vs AT and TT = 27.0% and 26.0%, P = 0.039). Patients having the AA genotype had a higher probability to remain on mechanical ventilation (P = 0.047) in the first 14 days. Lymphoblastoid cells having the AA genotype had significantly higher IL‐8 mRNA expression than cells having the AT or TT genotype (P = 0.022). Conclusions: Critically ill Caucasian patients who had the AA genotype of IL‐8 ?251A/T had an increased risk of PaO₂/FiO₂ <200. The AA genotype was associated with greater IL‐8 mRNA expression than the AT or TT genotypes.     

Maternal hypertension and intrapartum fever are associated with increased risk of ischemic stroke during infancy

Aim To examine maternal hypertension, diabetes, and intrapartum fever as potential risk factors for ischemic stroke in infants. Method We conducted a retrospective cohort study of 226 117 children born from January 2000 to December 2007 who were enrolled in the South Carolina Medicaid program. We linked maternal and child Medicaid billing records and birth certificate data. Children with ischemic stroke were identified based on the International Classification of Diseases, Ninth Revision (ICD‐9), code 434 in the child’s billing data. Independent variables and covariates were identified using ICD‐9 codes and birth certificate data. We modeled the odds of ischemic stroke diagnosis in infants, either before 30 days of life or before 365 days. Results Forty‐three children were diagnosed with ischemic stroke before 30 days and 161 before 365 days. Maternal hypertension (odds ratio 2.31 before 30d) and intrapartum fever (odds ratio 3.36 <30d) were significantly associated with odds of ischemic stroke before 30 days and before 365 days; maternal diabetes was not. Interpretation Maternal hypertension and intrapartum fever appear to be risk factors for ischemic stroke in infants. Additional research is needed to determine the mechanism(s) underlying these associations and to develop effective preventive methods for high‐risk infants.     

Dieting and its Relationship to Smoking,Acculturation, and Family Environment in Asian and Hispanic Adolescents

The objective of this article was to examine dieting and its relationship to smoking behaviors and attitudes, acculturation, and family environment in an ethnically diverse sample of adolescents. Participants were 211 adolescent girls and boys: 57% Asian, 16% Hispanic, 27% White. Regular dieting was determined using the Restraint Scale (Herman, 1978). Dependent variables were measured using the Smoking Beliefs and Attitude Questionnaire (Pederson & Lefcoe, 1985), Family Functioning in Adolescence Questionnaire (Roelofse & Middleton, 1985), and Suinn-Lew Asian Self-Identity Acculturation Scale (Suinn, Rickard-Figurroa, Lew, & Vigil, 1987). Dieting girls, as compared to nondieters, had more favorable attitudes toward smoking, more strongly believed that smoking keeps one from eating, and first experimented with cigarettes at an older age. Chronic dieting was related to reports of poorer family functioning, and Asian dieters were more acculturated than nondieters. For boys, there was no relationship between dieting and smoking, acculturation, or family environment. Smoking prevention programs targeted toward ethnic minority adolescent females need to address the issue of weight concern.     

THE P300 EVENT RELATED POTENTIAL COMPONENT IN THE DIAGNOSIS OF DEMENTIA

Several studies have suggested that delays in the latency of the P300 ERP component are highly sensitive and specific to dementia and that ERP measurements may become a useful clinical tool in aiding diagnosis. This study examines the sensitivity of P300 measurements to dementia and addresses several methodological issues that limit previous research. Twenty-four patients with dementia diagnosed according to ICD-10 criteria were compared with 100 normal controls, 31 of whom were older than 60. An auditory oddball paradigm was employed to elicit the P300. Mean P300 latency did not differ significantly between the two groups. When individual subjects were examined only 13% of patients with dementia fell outside the two standard error band of the regression of P300 latency on age derived from controls. Thus, this study has not demonstrated clinically useful abnormalities of the P300 component in dementia.     

Elevation of gastric pH heals peptic oesophagitis - A role for omeprazole

The aim of this study was to investigate the hypothesis that the prolonged and substantial elevation of gastric pH which can be achieved with the antisecretory agent omeprazole will result in healing of peptic oesophagitis. Eight patients with erosive or ulcerative peptic oesophagitis were treated with omeprazole (30 mg daily) for 8 weeks. Complete healing occurred in seven patients after 8 weeks of omeprazole therapy. Only a small area of residual ulceration persisted in one unhealed patient. Heartburn resolved within the first 2 weeks of therapy in all but one patient. Specific food intolerances also were eliminated in most cases. Post-prandial oesophageal pH monitoring during omeprazole administration showed abolition of acid reflux episodes (pH < 4). This effect appeared to be due solely to the antisecretory effect of omeprazole, since motility measurements demonstrated a continued high frequency of reflux while concurrent gastric pH monitoring showed sustained elevation of gastric pH above 4. These results support the hypothesis that a prolonged and potent inhibition of gastric acid secretion renders refluxed gastric juice sufficiently innocuous to allow healing of severe peptic oesophagitis.