Anisotropic magnetic interactions in the primary radical ion-pair of photosynthetic reaction centers

The quantum yield of triplets formed by ion-pair recombination in quinone-depleted photosynthetic reaction centers is found to depend on their orientation in a magnetic field. This new effect is expected to be a general property of radical pair reactions in the solid state. For 0 < H < 1,000 G, the quantum yield anisotropy is caused by anisotropic electron dipole-electron dipole or nuclear hyperfine interactions, or both. For high fields it is dominated by the anisotropy of the difference g-tensor in the radical ion-pair. The magnitude and sign of the contribution of each interaction depend not only on the values of the principal components of each anisotropic tensor but also on the geometric relationship of the principal axes of each tensor to the transition dipole moment used to detect the yield. A detailed formalism is presented relating these quantities to the observed yield anisotropy. The expected magnitude of each anisotropic parameter is discussed. It is demonstrated that the field dependence of the yield anisotropy is consistent with these values for certain reaction center geometries.     

Auditing paediatric diabetes care and the impact of a specialist nurse trained in paediatric diabetes

AIMS: To define outcome measures for auditing the clinical care of children and adolescents with insulin dependent diabetes mellitus (IDDM) and to assess the benefit of appointing a dedicated paediatric trained diabetes specialist nurse (PDSN). METHODS: Retrospective analysis of medical notes and hospital records. Glycaemic control, growth, weight gain, microvascular complications, school absence, and the proportion of children undergoing an annual clinical review and diabetes education session were assessed. The effect of the appointment of a PDSN on the frequency of hospital admission, length of inpatient stay, and outpatient attendance was evaluated. RESULTS: Children with IDDM were of normal height and grew well for three years after diagnosis, but grew suboptimally thereafter. Weight gain was above average every year after diagnosis. Glycaemic control was poor at all ages with only 16% of children having an acceptable glycated haemoglobin. Eighty five per cent of patients underwent a formal annual clinical review, of whom 16% had background retinopathy and 20% microalbuminuria in one or more samples. After appointing the PDSN the median length of hospital stay for newly diagnosed patients decreased from five days to one day, with 10 of 24 children not admitted. None of the latter was admitted during the next year. There was no evidence of the PDSN affecting the frequency of readmission or length of stay of children with established IDDM. Non-attendance at the outpatient clinic was reduced from a median of 19 to 10%. CONCLUSIONS: Outcome measures for evaluating the care of children with IDDM can be defined and evaluated. Specialist nursing support markedly reduces the length of hospital stay of newly diagnosed patients without sacrificing the quality of care.     

Serum leptin concentrations in relation to pubertal development

OBJECTIVES: The amount of adipose tissue influences pubertal development and fertility in girls. A candidate for mediating this is the hormone leptin, derived from adipocytes. This work was carried out to determine whether the leptin concentration in serum is regulated during pubertal development. SUBJECTS AND METHODS: Serum concentrations of leptin were determined by radioimmunoassay in a sample of 252 healthy children representing all pubertal stages. RESULTS: Serum leptin concentrations correlated directly with age (r = 0.53), body mass index (BMI) (r = 0.71), and weight for height SD score (r = 0.44) in girls and with BMI (r = 0.33) and weight for height SD score in boys (r = 0.36). Leptin concentrations increased with pubertal development in girls, resulting in significantly higher concentrations at pubertal stages 4 and 5 than at the prepubertal stage, whereas there was no change in the boys. CONCLUSIONS: Serum leptin concentrations increased during pubertal development in the girls, but remained constant in the boys. Whether the increase in serum leptin concentrations in girls is of importance for, or a consequence of, pubertal development is still to be determined.     

Proliferative lesions of oviduct and uterus in CD-1 mice exposed prenatally to tamoxifen

Tamoxifen (TAM) is widely used as adjuvant breast cancer therapy after surgery and as a chemopreventive agent in women of child-bearing age. However, TAM therapy has been shown to result in an increased incidence of endometrial carcinoma in women. The present study was designed to investigate the effects of TAM (5 mg/kg and 7.5 mg/kg body wt) given i.g. to pregnant CD-1 mice (1x/day, days 12 through 18 of gestation) on their female offspring. Progressive proliferative hyperplasia of the oviduct was frequently seen in TAM-exposed offspring, reaching 100% incidence by 52 weeks in both treatment groups. These females also developed progressive proliferative uterine lesions, including moderate/severe cystic endometrial hyperplasia (34-50%) and polypoid adenomas (27-30%) between 53 and 78 weeks. Deciduomas (15%) occurred at young ages (12 and 24 weeks) while leiomyomas (14%), a malignant leiomyosarcoma, and ovarian granulosa cell tumors (14%), were found between 72 and 78 weeks. Our findings thus suggest a strong association between transplacental TAM and reproductive tract abnormalities in female CD-1 mice.      

The efficacy of the ketogenic diet-1998: a prospective evaluation of intervention in 150 children

OBJECTIVE: The ketogenic diet is a high-fat, low-protein, low-carbohydrate diet developed in the 1920s for the treatment of children with difficult to control seizures. Despite advances in both the pharmacotherapy and the surgery of epilepsy, many children continue to have difficult-to-control seizures. This prospective study sought to determine the ketogenic diet's effectiveness and tolerability in children refractory to today's medications. METHODS: One hundred fifty consecutive children, ages 1 to 16 years, virtually all of whom continued to have more than two seizures per week despite adequate therapy with at least two anticonvulsant medications, were prospectively enrolled in this study, treated with the ketogenic diet, and followed for a minimum of 1 year. Seizure frequency was tabulated from patients' daily seizure calendars and seizure reduction calculated as percentage of baseline frequency. Adverse events and reasons for diet discontinuation were recorded. RESULTS: The children (mean age, 5.3 years), averaged 410 seizures per month before the diet, despite an exposure to a mean of 6.2 antiepileptic medications. Three months after diet initiation, 83% of those starting remained on the diet and 34% had >90% decrease in seizures. At 6 months, 71% still remained on the diet and 32% had a >90% decrease in seizures. At 1 year, 55% remained on the diet and 27% had a >90% decrease in seizure frequency. Most of those discontinuing the diet did so because it was either insufficiently effective or too restrictive. Seven percent stopped because of intercurrent illness. CONCLUSIONS: The ketogenic diet should be considered as alternative therapy for children with difficult-to-control seizures. It is more effective than many of the new anticonvulsant medications and is well tolerated by children and families when it is effective.     

Mononucleosis syndrome and coincidental human herpesvirus-7 and Epstein-Barr virus infection

Two girls (a 5 year old and a 21 month old) experiencing mononucleosis syndrome with coincidental human herpesvirus (HHV)-7 and Epstein-Barr virus (EBV) infections are described. One patient had primary HHV-7 infection and reactivated EBV infection. The other had primary HHV-7 and EBV infections. These cases indicated that HHV-7 is capable of inducing infectious mononucleosis-like illness. Multiple herpesvirus infection in one of the patients also suggests that interaction among herpesviruses can occur in vivo. The consequence of this interaction may have clinical implications.     

3‐D optical coherence tomography of the laryngeal mucosa*

Laryngeal carcinoma is one of the commonest primary head and neck malignancy and the need for early identification is very important for successful treatment. Outpatient fibreoptic examination of the larynx is unreliable in differentiating benign, pre‐malignant and malignant lesions, and therefore surgeons have to rely on biopsies for a definitive diagnosis. This is an invasive procedure requiring general anaesthesia and may have a detrimental effect on the patient's voice. Conventional imaging modalities (ultrasound, computed tomography and magnetic resonance imaging) have a limited resolution and hence cannot give sufficient information on the extent or nature of laryngeal lesions. The aim of our study is to investigate the feasibility of optical coherence tomography (OCT) in imaging the normal larynx, to lay the foundations for an investigation of its ability to differentiate between benign and malignant disease. Ten tissue specimens from normal larynges were imaged with an 850 nm OCT system that was capable of providing both B‐scan (longitudinal or cross‐section) images as well as C‐scan (en‐face or images at constant depth). The en‐face OCT mode allowed us to reconstruct 3‐D OCT images of the tissue examined. Imaged specimens were processed with standard histopathological techniques and sectioned in the plane of the B‐scan OCT images. Haematoxylin–eosin stained specimens were compared with the OCT images thus collected. Preliminary results showed good correlation between OCT images and histology sections in normal tissue.