Genomic arrangement of a putative operon involved in maltose transport in the Mycobacterium tuberculosis complex and Mycobacterium leprae

A Mycobacterium bovis gene coding for a putative MalE maltose binding protein was cloned and its full-length sequence determined. Database searches revealed 99.9% identity with IpqY, encoding a putative sugar uptake protein from Mycobacterium tuberculosis strain H37Rv. The deduced protein product showed high sequence similarity to MalE-like proteins from a variety of bacterial species, including Mycobacterium leprae. Analysis of flanking database sequences from M. tuberculosis and M. leprae revealed the presence of malF-, malG- and malK-like genes. Comparison of these mycobacterial sequences with other maltose operons has allowed us to deduce a unique genomic arrangement of the genes involved in the uptake of maltose in members of the Mycobacterium tuberculosis complex and M. leprae.

Similarity in bilateral photoplethysmographic peripheral pulse wave characteristics at the ears, thumbs and toes

The characteristics of the photoplethysmography (PPG) pulse signal are body site specific, with pulses from the various peripheral sites showing differences in pulse transit time, strength and shape, and variation of each over time. The aim of this study was to determine the similarity in the right-left pulse characteristics for a group of normal subjects with pulses obtained simultaneously from six peripheral sites (cars, thumbs and big toes). A multi-site photoplethysmography pulse measurement and analysis system is described and comprised six sets of pulse probes and amplifiers, arranged and electronically matched in pairs for the right and left side comparisons. Two sets of data were collected: firstly a set of validation data to test the electronic matching of right left channels, and secondly a set of physiological data for pulses from 40 normal subjects. The right-to-left side similarity in pulse waveform shape at the three segmental levels (ears, thumbs and toes) was assessed using two types of analysis: root mean square error (RMSE) providing a measure of differences, and cross correlation analysis providing a measure of the degree of similarity. Very low levels of RMSE and correlation coefficients close to unity were obtained for the system validation data, demonstrating good right-left channel matching. The RMSE was an order of magnitude lower than that calculated for the normative physiological data, where median RMSE levels were between 0.053 and 0.060 relative to a peak-to-peak pulse amplitude of unity. The median correlation coefficients were greater than 0.98 for all three segmental levels studied, with the maximum values approaching those of the validation data. We have shown that pulses from the right and left sides of normal subjects are highly correlated at each segmental level. We have obtained a normative range of pulse data, with which specific (vascular) patient groups can be compared.

Computer model for study of cardiac repolarization

INTRODUCTION

We propose a new and simple method to model repolarization in the left ventricle and the corresponding T waves on the surface ECG.

METHODS AND RESULTS

We modeled the cardiac cell action potentials (APs) in the left ventricle (LV) with differences in only the duration of the plateau phase. Using published experimental data on the epicardial and endocardial repolarization sequences, for each point on the left ventricular surface we set a different AP repolarization starting time, determined by the duration of the plateau phase. The surface source model was used to compute potentials on the surface of the torso, generated by repolarization of the LV. Both the torso and the LV had homogeneous and isotropic conductivity. We simulated T waves on the 12-lead ECG and compared our results with measured T waves from five normal subjects. The orientation and shape in each lead were reproduced. In each lead we computed the root mean square error between simulated and measured T waves. The average error across the 12 leads was small, with a mean value of 0.11 mV across all the subjects.

CONCLUSION

Repolarization of the LV can be modeled independently of the depolarization sequence and AP duration gradients. This method is an easy and powerful tool to describe the ECG features of repolarization.

Stability and haplotype analysis of the FRAXE region

FRAXE full mutations are rare and appear to be associated with mild mental retardation. As part of a screening survey of boys with learning difficulties to determine the frequency of full and premutations, we have collected data on the frequency of instability at FRAXE for about 4000 transmissions and the haplotype for over 7000 chromosomes. The distribution of FRAXE repeats was similar to other English populations but differed from two North American Caucasian series. Observed instability at FRAXE was rare but increased with increasing repeat number, and there were no expansions into the full mutation range, except in pedigrees ascertained through a full mutation. Haplotype analysis suggested division into five groups with each group having a characteristic distribution of FRAXE repeats. Fourteen of the 15 full mutations occurred on a single haplotype and this haplotype also had a significant excess of intermediate-sized alleles, suggesting that full mutations originate from large normal alleles. However, a related haplotype also had a significant excess of intermediates but we observed no full mutations on this haplotype, suggesting either loss or gain of stability determinants on it. We suggest that whilst triplet repeat size is a significant predisposing factor for expansion at FRAXE other genetic determinants are also likely to be important.

Adefovir dipivoxil for the treatment of lamivudine-resistant hepatitis B mutants

Lamivudine has been shown to be an effective therapy for chronic hepatitis B, but resistance to this nucleoside agent is common after prolonged use. Five patients with chronic hepatitis B virus (HBV) infection developed resistance to lamivudine after 9 to 19 months of treatment. In 4 patients this occurred after liver transplantation and the remaining individual had stable cirrhosis. In each case, resistance was confirmed to be caused by one or more mutations in the HBV-DNA polymerase gene and was associated with active underlying liver disease. The patients were treated with adefovir dipivoxil in a dose of 5 to 30 mg daily. Two to 4 log(10) reductions in HBV-DNA levels were observed in 4 cases, and the fifth patient became negative by quantitative polymerase chain reaction (PCR) after retransplantation in conjunction with hepatitis B immunoglobulin (HBIg). Virologic improvement was associated with stable or declining serum alanine transaminase levels in 4 patients. HBV-DNA suppression has been sustained during a mean treatment period of 13 months (range 11 to 15 months), including 1 patient in whom lamivudine has been discontinued. Mild changes in renal function were observed during treatment in most cases but did not require early discontinuation of the drug. This study provides evidence that adefovir dipivoxil can be an effective treatment for lamivudine-resistant HBV mutants as well as wild-type HBV.

FRAXA and FRAXE: the results of a five year survey

We report the results of a five year survey of FRAXA and FRAXE mutations among boys aged 5 to 18 with special educational needs (SEN) related to learning disability. We tested their mothers using the X chromosome not transmitted to the son as a control chromosome, and the X chromosome inherited by the son to provide information on stability of transmission. We tested 3738 boys and 2968 mothers and found 20 FRAXA and one FRAXE full mutations among the boys and none among the mothers. This gives an estimated prevalence of full mutations in males of 1 in 5530 for FRAXA and 1 in 23 423 for FRAXE. We found an excess of intermediate and premutation alleles for both FRAXA and FRAXE. For FRAXA this was significant at the 0.001 level but the excess for FRAXE was significant only at the 0.03 level. We conclude that the excess of intermediate and premutation sized alleles for FRAXA may well be a contributing factor to the boys' mental impairment, while that for FRAXE may be a chance finding. We studied approximately 3000 transmissions from mother to son and found five instabilities of FRAXA in the common or intermediate range and three instabilities of FRAXE in the intermediate range. Thus instabilities in trinucleotide repeat size for FRAXA and FRAXE are rare, especially among alleles in the common size range.

Synthesis of FF-MAS from lithocholic acid

An effective synthesis of 4,4 dimethyl-cholest-8,14,24-trien-3beta-ol (FF-MAS) from lithocholic acid is described, utilising a double oxidation and regioselective Wittig reaction as key steps.

Do patients with ankylosing spondylitis have poorer balance than normal subjects?

OBJECTIVES

To investigate whether patients with ankylosing spondylitis have poorer balance than normal subjects, and to study the relationship between balance and posture.

METHODS

Balance was studied in 30 ankylosing spondylitis subjects using sway magnetometry, making quantitative measurements of movement at the hips with eyes open and eyes closed. The results were compared with data from 58 normal subjects. Balance was also compared with quantitative measurements of posture.

RESULTS

The numbers of patients with poor balance, above the 95th percentile for normal, were significantly greater than expected; 18% for eyes open (P = 0. 03) and 23% for eyes closed (P = 0.004). No significant relationships between balance and any of the quantitative descriptions of posture were demonstrated.

CONCLUSION

A significant proportion of ankylosing spondylitis patients have poorer balance than normal subjects.

Low-dose continuous-infusion ceftazidime monotherapy in low-risk febrile neutropenic patients

One hundred and thirty-five cancer patients admitted with low-risk neutropenic fever received a low-dose schedule of ceftazidime as infusional monotherapy over a total of 180 episodes. Ceftazidime was administered as a 1-g bolus followed by a continuous infusion of 2 g per day. In this patient population the ceftazidime was both practical and well tolerated. Sixty-eight percent of patients responded with clinical improvement and complete resolution of fever within 48 h. Overall, 95% of patients responded, although 18% subsequently required antibiotic modification for persistent fever. Only 5% of episodes were considered failures due to clinical deterioration, and over the study period there was only 1 fatality due to respiratory failure. The median duration of hospitalisation was only 4 days (2-20). In conclusion, monotherapy with low-dose infusional ceftazidime appears safe and highly effective in this low-risk population of neutropenic patients and may reduce antibiotic costs appreciably.

Heart rate and blood pressure variability in normal subjects compared with data from beat-to-beat models developed from de Boer's model of the cardiovascular system

The objective of this study was to assess the ability of de Boer's model of the cardiovascular system to reproduce the heart rate and blood pressure variability observed in a range of normal subjects, and to make modifications to improve its performance. ECG, blood pressure and chest wall movement were recorded from 12 normal human subjects during controlled breathing. For each beat, systolic pressure, diastolic pressure, arterial time constant and RR interval were extracted. RR interval and systolic pressure spectral power in low and high frequency bands and the baroreflex sensitivity index, alpha, were then determined. For each subject, mean values were input to the model and the beat-to-beat output compared with the actual data for that subject. Finally, the effects of reducing the influence of baroreflex on peripheral vascular resistance and of providing separate sympathetic and vagal baroreflex sensitivities were assessed. Simulations resulted in data which were qualitatively similar to those of each subject's recording. With the modifications, the log ratio of simulated to real data improved from 7.2 to 1.5 (p = 0.003) for low frequency RR, from 0.27 to 0.55 (p = 0.011) for high frequency RR and from 8.5 to 0.9 (p = 0.003) for low frequency systolic pressure. We conclude that de Boer's model reproduces many of the characteristics of heart rate and blood pressure variability, and our modifications to baroreflex sensitivities and the feedback effect on peripheral resistance resulted in significant improvements.

Excision of nasopharyngeal angiofibroma facilitated by intra-operative 3D-image guidance

The latest 3D-image guidance systems to assist surgeons have greatly improved over earlier models. We describe the use of an optical infra-red system to assist in the removal of a juvenile nasopharyngeal angiofibroma. The specific advantages of this system in pre-operative assessment, intra-operative evaluation and excision of the angiofibroma are discussed.

The clinical value of septal perforation biopsy

Biopsy from the edge of a septal perforation is performed to diagnose potentially significant aetiological conditions, including malignant pathology and Wegener's granulomatosis. However, it is common for the histological result to be undiagnostic and unhelpful in planning an individual patient's management. To clarify the role of septal perforation biopsy, we reviewed all biopsies performed on our patients over a 13-year period. Of the 65 biopsies performed, in 63 patients, none had a histological result which changed the clinical diagnosis made before biopsy. Forty-three patients had clinically benign perforations biopsied, and no histology other than chronic inflammation was obtained. In 16 patients with a clinical vasculitis, none had this diagnosis confirmed histologically. One positive biopsy was obtained from two patients with clinically malignant perforations yet both were treated for T-cell lymphoma. The subsequent management of all patients was based on their clinical diagnosis rather than their biopsy results. We suggest only clinically malignant perforations are worthwhile biopsying.

Part-time physicians. Physician workload and patient-based assessments of primary care performance

OBJECTIVE

To examine the relationship between the number of hours physicians work and patients' assessment of the physician.

DESIGN

Cross-sectional study with physician and patient surveys.

SETTING

Primary care practices in Massachusetts.

PARTICIPANTS

A random sample of 6810 Massachusetts state employees in 15 different health plans.

MAIN OUTCOME MEASURES

Eleven summary scales measuring 7 essential elements of primary care. Information was derived from the Primary Care Assessment Survey, a validated patient-completed questionnaire.

RESULTS

Physicians were classified into 3 groups according to their reported hours of work: "overtime" (> 65 h/wk), "full time" (40-65 h/wk), and "part time" (< 40 h/wk). There was no statistically significant difference between the 3 groups of physicians in 10 of the 11 measures of primary care performance. Physicians who worked more than 65 hours per week were found to score significantly higher in the visit-based continuity of care category than physicians working fewer hours. Physicians working more than 65 hours per week were also found to be significantly less satisfied with the amount of time they had for family and personal life than the other 2 groups.

CONCLUSIONS

Part-time physicians perform as well as full-time physicians in most aspects of primary care, including all interpersonal aspects of care, as reported by patients. Patients of physicians working more than 65 hours per week experienced higher levels of visit-based continuity of care than patients of physicians working fewer hours, but this appears to carry a cost to those physicians in the area of personal and professional satisfaction. Subsequent research should examine the relationship between physician workload and technical aspects of care.

Reproductive and menstrual history of females with fragile X expansions

FRAXA premutations have been associated with premature ovarian failure (POF) or menopause before the age of 40. We have studied women in families ascertained because of a mentally retarded full mutation relative and determined their age of menopause, serum hormone levels in premenopausal individuals and the outcome of any pregnancies. Survival analysis was used as a measure of menopause and demonstrated a significant decrease in age of menopause in premutation carriers compared with their full mutation carrier and normal relatives. Serum FSH was also raised in premutation carriers, although oestradiol, inhibin A and inhibin B were not significantly different. However, we did not find an excess of dizygous twins or pregnancy loss/trisomies, both of which are associated with aging ovaries. Thus premutation carriers as a group have an earlier menopause and raised serum FSH but do not appear to manifest other features of an aging ovary.

Failure of founder transgenic male mice to transmit an attenuated HSV thymidine kinase transgene results from mosaicism and sperm competition

Previously we found that male mice carrying either of two attenuated herpes simplex virus thymidine kinase reporter transgenes displayed low level ectopic expression of the reporter gene in the testis and, although fertile, exhibited reduced fecundity. In contrast to males of later generations, many of the founder males failed to transmit the transgene to their progeny. This led to the suggestion that these fertile non-transmitting males are mosaic, with the sperm developing from the non-transgenic lineage outperforming those from the heterozygous transgenic lineage. Here we present the results of artificial insemination (AI) and in vitro fertilization (IVF) experiments designed to test this hypothesis. Albino CF(1) hybrid females were inseminated with mixtures of equal numbers of sperm from heterozygous transgenic (HT) males (equivalent to C57BL/6 x CBAF(2)) and CF(1) males. Similar mixed inseminations were carried out in parallel with sperm from non-transgenic (NT) siblings of the HT mice and 13-day fetuses were scored by eye color to determine their paternity. The pooled data from five experiments gave ratios of CF(1) to HT and CF(1) to NT offspring of 8.13 and 0.22 respectively, implying a calculated HT to NT ratio of 0.027. This indicates that, in competition with each other, the NT sperm would be almost 40 times more successful in fertilization than the HT sperm. Smaller differences were observed between HT and NT when AI was performed with unmixed sperm, consistent with the fertility of HT non-founder males. However, in five IVF experiments carried out with unmixed sperm, 142/212 oocytes exposed to NT sperm were activated and divided, while only 8/226 oocytes treated with HT sperm reached the two-cell stage. This confirms that HT sperm are defective and indicates that the IVF method employed amplified these deficiencies, which may have only a small effect upon natural reproduction when the HT sperm are not in competition with normal sperm.

Pharmacokinetics of tramadol in children after i.v. or caudal epidural administration

We have studied the pharmacokinetics of a single bolus dose of tramadol 2 mg kg-1 injected either i.v. or into the caudal epidural space in 14 healthy children, aged 1-12 yr, undergoing elective limb, urogenital or thoracic surgery. Serum concentrations of tramadol and its metabolite O-demethyl tramadol (MI) were measured in venous blood samples at various intervals up to 20 h by non-stereoselective gas chromatography with nitrogen-selective detection. All pharmacokinetic variables were evaluated using a non-compartmental model. After a single i.v. injection (n = 9), the mean elimination half-life of tramadol was 6.4 (SD 2.7) h, with a volume of distribution of 3.1 (1.1) litre kg-1 and total plasma clearance of 6.1 (2.5) ml kg-1 min-1. All of these pharmacokinetic variables were similar to those reported previously in adults. After caudal epidural administration (n = 5), mean elimination half-life was 3.7 (0.9) h, volume of distribution was 2.0 (0.4) litre kg-1 and total clearance was 6.6 (1.9) ml kg-1 min-1. The caudal/i.v. quotient of the AUC was 0.83, which confirms that there is extensive systemic absorption of tramadol after caudal administration. Serum concentrations of MI showed a time course typical of a metabolite after both modes of administration. Serum concentrations of MI after caudal administration were lower than those after i.v. injection.

Effect of mating system, flushing procedure, progesterone dose and donor ewe age on the yield and quality of embryos within a MOET program in sheep

Multiple ovulation and embryo transfer (MOET) has the potential to increase the rates of genetic improvement in sheep. However, better realization of this potential requires a higher yield of transferable embryos. Thus we investigated some factors that may contribute to high embryo yield and quality under field conditions, as part of an ongoing MOET program. Comparison of the effects of 2 breeding systems (natural service plus laparoscopic intrauterine AI vs natural service only) on embryo yield and quality indicated that while AI did not affect embryo recovery, it significantly (P < 0.05) improved fertilization rate and embryo quality, and increased (P < 0.05) embryo survival rate after transfer to recipients. Two flushing procedures (the original semi-laparoscopic and a modified version) were compared for effects on embryo recovery. The modifications made to the original collection method increased (P < 0.001) embryo recovery from 69.0 +/- 2.4 to 83.2 +/- 0.6%. The effects of the progestagen priming dosage during superovulatory treatment and ewe age on MOET outcome were also investigated. Donor ewes primed with 30-mg progestagen sponges came into estrus 1.9 h earlier (P < 0.05) than those primed with 45-mg sponges, but there was no difference in ovulation rate or embryo recovery, or in embryo survival after transfer between the 2 regimens. However, Chi-square analysis indicated a significant benefit in favor of the higher progesterone dose on both fertilization (P < 0.01) and embryo quality (P < 0.001). Age of donor ewe did not significantly affect the timing of estrus, fertilization rate or embryo survival after transfer. While adult ewes had higher (P < 0.05) ovulation rates and embryo yields, shearling ewes produced a much higher proportion of Grade 1 embryos (P < 0.05).

Risk of recurrence of bipolar disorder in pregnant and nonpregnant women after discontinuing lithium maintenance

OBJECTIVE

Pregnancy poses major challenges for the treatment of bipolar disorder, and information to guide clinical care remains very sparse. The authors sought to determine the illness recurrence risk for women with bipolar disorder who discontinue lithium maintenance during pregnancy.

METHOD

The authors retrospectively compared recurrence rates and survival functions for 101 women with DSM-IV bipolar disorder (68 type I, 33 type II) during pregnancy and postpartum (N=42) or during equivalent periods (weeks 1-40 and 41-64) for age-matched nonpregnant subjects (N=59) after either rapid (1-14 days) or gradual (15-30 days) discontinuation of lithium. Recurrence rates also were obtained for the year before discontinuing lithium.

RESULTS

Rates of recurrence during the first 40 weeks after lithium discontinuation were similar for pregnant (52%) and nonpregnant women (58%) but had been much lower for both in the year before treatment was discontinued (21%). Among subjects who remained stable over the first 40 weeks after lithium discontinuation, postpartum recurrences were 2.9 times more frequent than recurrences in nonpregnant women during weeks 41-64 (70% versus 24%). Depressive or dysphoric-mixed episodes were more prevalent in pregnant than nonpregnant women (63% versus 38% of recurrences). Recurrence risk was greater after rapid than after gradual discontinuation, and for patients with more prior affective episodes, but was similar for diagnostic types I and II.

CONCLUSIONS

Rates of recurrence during the first 40 weeks after lithium discontinuation were similar for pregnant and nonpregnant women but then sharply increased postpartum. Risk was much lower during preceding treatment and less with gradual discontinuation. Treatment planning for potentially pregnant women with bipolar disorder should consider the relative risks of fetal exposure to mood stabilizers versus the high recurrence risks after discontinuing lithium.

Periorbital cellulitis secondary to ethmoiditis in a 5-week-old child

Periorbital cellulitis is a condition primarily affecting young children. We present a 5-week-old boy who developed periorbital cellulitis and had a CT scan which identified acute ethmoiditis as the source of the sepsis. His clinical course is outlined, and the relevant literature is discussed. We believe this patient is the youngest case of periorbital cellulitis due to confirmed ethmoiditis reported. This emphasises the possibility of an underlying sinusitis in patients with periorbital cellulitis, even in this very young age group.

Fulminant hepatic failure resulting from lamivudine-resistant hepatitis B virus in a renal transplant recipient: durable response after orthotopic liver transplantation on adefovir dipivoxil and hepatitis B immune globulin

BACKGROUND

Mutations in the hepatitis B virus (HBV) genome may occur during therapy.

METHODS

We report an asymptomatic HBV carrier who underwent transplantation for end-stage renal disease. She developed an HBV flare 6 months after transplantation and was placed on lamivudine. After initial rapid improvement, she relapsed clinically and virologically. She decompensated with jaundice, peripheral edema, ascites, encephalopathy, coagulopathy, and hepatorenal syndrome. A liver biopsy specimen revealed submassive necrosis.

RESULTS

Emergency liver transplantation was performed: lamivudine was discontinued. Hepatitis B immunoglobulin and adefovir dipivoxil were initiated. Sixteen months after orthotopic liver transplantation, she is HBV DNA seronegative with normal liver enzymes. Sequencing of HBV polymerase gene from preliver transplantation sera did not detect the usual lamivudine resistance mutations in the YMDD motif but instead two other mutations (F514-->L, L528-->M). Lamivudine resistance was demonstrated in vitro.

CONCLUSIONS

Asymptomatic HBV carriers may reactivate following renal transplantation after immunosuppression. Resistance to lamivudine may result in severe hepatic damage in immunocompromised patients.