Improved sensitivity to cerebral hemodynamics during brain activation with a time-gated optical system: analytical model and experimental validation

Time domain (TD) diffuse optical measurement systems are being applied to neuroimaging, where they can detect hemodynamics changes associated with cerebral activity. We show that TD systems can provide better depth sensitivity than the more traditional continuous wave (CW) systems by gating late photons, which carry information about deep layers of the brain, and rejecting early light, which is sensitive to the superficial physiological signal clutter. We use an analytical model to estimate the contrast due to an activated region of the brain, the instrumental noise of the systems, and the background signal resulting from superficial physiological signal clutter. We study the contrast-to-noise ratio and the contrast-to-background ratio as a function of the activation depth and of the source-detector separation. We then present experimental results obtained with a time-gated instrument on the motor cortex during finger-tapping exercises. Both the model and the experimental results show a similar contrast-to-noise ratio for CW and TD, but that estimation of the contrast is experimentally limited by background fluctuations and that a better contrast-to-background ratio is obtained in the TD case. Finally, we use the time-gated measurements to resolve in depth the brain activation during the motor stimulus.     

Flucloxacillin associated neutropenia in children treated for bone and joint infections

OBJECTIVE: This report describes episodes of acute neutropenia associated with flucloxacillin use in children treated for bone and joint infections. METHODS: A retrospective chart audit was performed on eight children who developed neutropenia when treated with flucloxacillin. RESULTS: Eight children (aged 1 month to 13 years) had a diagnosis of neutropenia attributed to treatment with flucloxacillin, seven of whom received parenteral therapy. The time to onset of neutropenia averaged 27 days, with neutrophil counts returning to normal limits in all patients after 2 to 9 days. Two children were asymptomatic when the neutropenia was detected. The average flucloxacillin dose used was 65% (range 20-100%) of the recommended maximum dose. CONCLUSIONS: These cases suggest that flucloxacillin should be used with greater caution and guidelines for dosing and clinical monitoring (regular neutrophil counts) need to be reassessed, despite none of these patients experiencing serious sequelae.     

Does routine blood bone biochemistry predict vitamin D insufficiency in elderly patients with low-velocity fractures?

PURPOSE: Vitamin D deficiency impairs bone mineralisation and can predispose individuals to fractures. This study aimed at testing whether measurement of plasma calcium, alkaline phosphatase, and phosphate levels could detect vitamin D insufficiency. METHODS: During a 10-week winter period from December 2000 to February 2001, all elderly patients presenting to a general hospital in Brighton--British seaside town--with a fracture of the proximal femur and without known bone mineralisation problems were invited to participate in the study. RESULTS: 23 (63.9%) of the 36 eligible patients had insufficient levels of vitamin D, with a plasma concentration of less than 30 nmol/L. The mean parathyroid hormone level was 56 pg/mL (range, 12-193 pg/mL). 11 of the 36 patients had an elevated level of parathyroid hormone were insufficient in vitamin D. The mean plasma concentration of calcium was 2.30 mmol/L (range, 2.05-2.98 mmol/L). The mean phosphate level was 0.98 mmol/L (range, 0.40-1.79 mmol/L), and the mean alkaline phosphatase level was 91 IU/L (range, 46-127 IU/L). There was poor correlation between vitamin D insufficiency and plasma calcium, alkaline phosphatase, or phosphate levels. CONCLUSION: Plasma calcium, alkaline phosphatase, and phosphate testing cannot detect vitamin D insufficiency. We recommend that vitamin D and calcium supplementation be considered for patients with low-energy hip fractures.     

Chronic fuel oil toxicity in American mink (Mustela vison): systemic and hematological effects of ingestion of a low-concentration of bunker C fuel oil

Petroleum oil enters the coastal marine environment through various sources; marine mammals such as sea otters that inhabit this environment may be exposed to low concentrations of petroleum hydrocarbons through ingestion of contaminated prey. The inability to perform controlled studies in free-ranging animals hinders investigations of the effects of chronic petroleum oil exposure on sea otter morbidity and mortality, necessitating the development of a reliable laboratory model. We examined the effects of oral exposure to 500 ppm bunker C fuel oil over 113-118 days on American mink, a species phylogenetically related to the sea otter. Hematological parameters and organs were examined for fuel oil-associated changes. Hepatic cytochrome P4501A1 mRNA expression and fecal cortisol concentrations were also measured. Ingestion of fuel oil was associated with a decrease in erythrocyte count, hemoglobin concentration (Hgb), hematocrit (HCT), and an increase in mean corpuscular volume (MCV). Total leukocytes were elevated in the fuel oil group from increases in neutrophils, lymphocytes, and monocytes. Significant interactions between fuel oil and antigen challenge were found for erythrocyte parameters, monocyte and lymphocyte counts. Liver and adrenal weights were increased although mesenteric lymph node weights were decreased in the fuel oil group. Hepatic cytochrome P4501A1 mRNA was elevated in the fuel oil group. Fecal cortisol concentration did not vary between the two groups. Our findings show that fuel oil exposure alters circulating leukocyte numbers, erythrocyte homeostasis, hepatic metabolism and adrenal physiology and establish a framework to use mink as a model for sea otters in studying the systemic effects of marine contaminants.     

The aetiology of specific language impairment: no evidence of a role for obstetric complications

Summary. The role of obstetric complications (OCs) in Specific Language Impairment (SLI) has been investigated, but the relationship remains unclear. This study investigates the association between SLI and OCs in a sample of 194 children, participants in a family study of SLI. Initial analyses utilising a traditional case-control approach found no evidence of an association. The effect of changing the case criteria was explored, but the finding of no association remained. The relationship between OCs and various language measures was also investigated using continuous data analytic techniques. This supported the findings of the case control analysis of no association. Previous reports have suggested a specific role for either hypertension or toxaemia in pregnancy. This study found no evidence for an association between these complications of pregnancy and SLI. This study found no evidence to support an aetiological role of OCs in SLI.     

The detection of psychological problems by General Practitioners

BACKGROUND: Common mental illness in Black Africans and Black Caribbeans has been relatively little studied in the UK. Previous studies of the detection of psychological problems by General Practitioners (GPs) in these groups have been inconclusive. AIMS: The aim of this study was to investigate the prevalence, detection and management of psychological problems in General Practice among Black Caribbeans and Black Africans compared to White English attenders and to examine the relative contribution of other sociodemographic factors to these main outcome variables. METHOD: Consecutive attenders aged 16-65 years at 18 General Practitioners in South-East London completed the General Health Questionnaire (GHQ-12) before seeing the GP. The GPs rated the current emotional state of the patients at the end of each consultation. Comparison of the GHQ and GP ratings was used to compute the detection indices. RESULTS: A total of 1211 patients aged 16-65 years were approached to take part in the study. Of the patients, 75 (6%) declined or were not able to complete the GHQ. In all, 994 individuals had both GP and GHQ ratings. There was an overall probable prevalence of 37%, of which 73% were identified as cases by the GPs. Black African patients had lower rates of common mental disorders, were less likely to be detected as psychiatric cases by the GP and less likely to receive active management for their psychological problems than Black Caribbean and White English patients. Rates of prevalence, detection and management were similar between Black Caribbean and White English patients. In the multivariate analysis, ethnicity, employment and age all played a significant independent role in predicting probable prevalence. The patients' reported decision to talk to their GP about psychological problems was the main predictor of detection. Ethnicity did not independently predict detection, but Black African cases were less likely to say that they would talk to their GP about psychological problems. GPs' identification indices mirrored probable prevalence, suggesting that GPs were more sensitive to detecting psychiatric illness in individuals belonging to groups which commonly presented as symptomatic. CONCLUSIONS: The findings suggest that in General Practice the prevalence of common mental disorders, their detection and management in Black Caribbeans are similar to those in White English, but that Black Africans have lower prevalence, are less likely to be detected and are less likely to receive active management. The study of GP consulters presents problems for the interpretation of these results and it may be that Black Africans with psychological problems are less likely than their Caribbean and English counterparts to attend their GP, and less willing to speak to them about these problems when they do. Future similar studies should distinguish Black African and Black Caribbean subjects in their analyses, as categories such as 'Afro-Caribbean' may mask important differences in attitudes and illness behaviour.