Clostridium difficile-associated clinical burden from lack of diagnostic testing in a Chinese tertiary hospital

Despite Clostridium difficile infection (CDI) being a common cause of diarrhoea in hospitals worldwide, diagnostic testing or management guidelines are not available in most hospitals in China. In this prospective two-year study, the incidence of CDI among 276 patients with watery diarrhoea was 23.1%. Lack of diagnostic testing for CDI was associated with improper management in 26.4% of patients, risk of nosocomial transmission from lack of isolation precautions, and risk of community transmission from discharging symptomatic toxigenic C. difficile carriers. Updating practice guidelines in line with the current evidence and implementing diagnostic testing for CDI are recommended in hospitals in China.

Novel de novo BRCA1 mutation in a woman with early onset breast cancer

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Background: Germline mutations in BRCA1/2 account for a significant portion of hereditary breast/ovarian cancer. Mutation carriers usually have a family history of breast/ovarian cancer or early onset disease. Rarely, germline mutations are found only in the probands but not in any family members. Such de novo mutations have been reported in diseases such as hemophilia A, thalassaemia and familial adenomatous polyposis. De novo mutations in the BRCA1 or BRCA2 genes are rare and the few reported have been in BRCA2. Here, we describe de novo as well as novel mutation of the BRCA1 gene in a breast cancer patient. Methods: Blood DNA samples from a 30 year old Chinese woman with breast cancer and no family history of cancer was tested for a BRCA1/2 mutation by full gene sequencing and Multiple Ligation-dependent Probe Amplification (MLPA). Family members were analyzed for the same mutation. Paternity was determined by a set of highly polymorphic short tandem repeat (STR) markers. Results: Full gene sequencing found no deleterious mutation. MLPA revealed a large deletion of exons 1 to 12 of BRCA1 in the proband. MLPA performed on 5 family members: proband's mother and father (who were 1st degree relative- cousins), stepmother (mother's biological sister), 2 sisters (1, same parents; 1, same father and stepmother) found no similar deletion. By using a set of highly polymorphic STR markers, the proband's father and mother were confirmed to be her biological parents. Conclusions: We report a novel de novo BRCA1 deletion mutation encompassing exons 1 - 12 in a Chinese breast cancer patient of early onset with no family history. Identification of this large deletion confirms the importance of pursuing rearrangement testing if full gene sequencing fails to detect a point mutation or short insertion deletion. The mutation found in this study is de novo. This may simply be a random mutation event which occurred in the parents' germ cells during their lifetime which passed onto one of their offspring or maybe a result of gene inversion or splicing deficiency. The relations of such mutations with consanguineous marriage cannot be ruled out. Mutation screening is important in early onset breast cancer patients even if there is no family history.

No significant financial relationships to disclose.

Clinical and pathological characteristics of Chinese patients with BRCA related breast cancer

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Background: Breast cancers due to underlying germline BRCA1 and BRCA2 mutations are associated with particular pathological features that may differ from sporadic breast cancers. We report clinical and pathologic characteristics of breast cancer in a clinical cohort of high risk Chinese women with BRCA mutations and those without mutations. Methods: 202 high risk women based on their age and family history were recruited from March 2007 to November 2008. Medical information was prospectively collected from the patients and medical records. BRCA1 and BRCA2 mutations were detected using full gene sequencing and multiplex ligation-dependent probe amplification (MLPA). Results: Of the 202 female probands tested, 25 (12.3 %) were BRCA mutation carriers of which 11 (44%) were BRCA1 and 14 (56%) were BRCA2 mutations. Breast cancer risk factors, other than family history, did not differ between carriers and non-carriers. Mutation carriers were more likely to have a familial history of breast cancer (p=0.07) and personal and family history of ovarian cancer (p=0.005; p=0.007). Other cancers found in carriers families included pancreatic, gastric, colon, lung, liver, and nasopharyngeal. 23% of women diagnosed with DCIS had BRCA mutations compared with 11.4% of those with invasive cancers. BRCA related tumors were more likely to be ER, PR and Her-2 negative (Triple negative, TN) (p= 0.006). Overall 9.6% of non-BRCA cancers were TN whereas 25.9% of BRCA cancers were TN. Prevalence of TN in BRCA1 carriers is 71% compared with 13.4% in BRCA2 carriers. BRCA1 mutation related cancers were significantly more likely to be ER negative than BRCA2 and this is only significant in those who are under 40 years of age (p=0.070). Conclusions: We have a high BRCA2 mutation rate in our cohort. BRCA related breast cancer is associated with families with increasing number of first degree relatives with breast and/or ovarian cancers and were higher for DCIS cancers. Prevalence of TN breast cancers was high compared to Caucasian cohorts. BRCA mutations were associated with pathologically, poor prognostic features (TN and high grade) especially in younger women.

No significant financial relationships to disclose.

Knowledge, attitudes and practices regarding evidence-based medicine and outcome assessment: a survey of British Columbia cataract surgeons

BACKGROUND

While the advantages of practising evidence-based medicine are well-documented, it is frequently suggested that doctors' attitudes are a major roadblock to its implementation. We carried out a survey to determine the knowledge, attitudes and practices of British Columbia cataract surgeons regarding evidence-based medicine and outcome assessment.

METHODS

The survey was conducted in the spring of 1999. The study population was drawn from the directory of the British Columbia College of Physicians and Surgeons. A 16-item questionnaire designed to elicit the knowledge of, attitudes toward and use of evidence-based medicine and outcome assessment was sent to all surgeons performing cataract surgery in British Columbia.

RESULTS

Of the 103 eligible participants, 70 (68%) returned completed questionnaires. Surgeons affiliated with the University of British Columbia were more likely to respond than those not affiliated with the university (81% vs. 58%) (p < 0.05). Most surgeons (89%) viewed the responsibility of monitoring quality of care as primarily their own. Although 79% of the respondents felt that outcome assessment is an effective method for determining quality of care, less than half (49%) reported that they routinely include some form of outcome assessment in their clinical practice. There was wide variation in the respondents' understanding of the nature of outcome assessment and evidence-based medicine. Respondents professed little inclination or motivation to committing time or resources to an outcome program. They also expressed concerns over the use of outcome data for external management activities.

INTERPRETATION

Cataract surgeons in British Columbia clearly appreciate the advantages of outcome assessment, but translation of this understanding into practice is limited. There appears to be a need for further education on outcome assessment and evidence-based medicine through academic bodies and professional societies.

Abuse and deliberate self-poisoning in women: a matched case-control study

OBJECTIVE

Controlled studies have shown deliberate self-harm to be more common in abused populations, but no controlled studies have shown abuse to be more common in self-harming populations. This is the first controlled study to determine whether abuse experiences (sexual, physical, and psychological) occurred more commonly in women who take overdoses than in controls.

METHOD

The design was a matched (1:1) case-control study set in a district general hospital in England. The subjects were 36 women admitted following deliberate self-poisoning. They were matched with the next non-overdose admission to the same hospital on six variables (sex, age, ethnicity, social class, marital status, and geographical locality). The main outcome measures used were modified versions of standardized self-report questionnaires of sexual, physical, and psychological abuse, together with measures of parenting style and general psychopathology.

RESULTS

Women who had taken an overdose were more likely (odds ratio 15.0, 95% confidence interval 2.0 to 113.6) to have been sexually abused, and somewhat more likely to have been psychologically (1.02, 1.00 to 1.05) but not physically abused. They also had higher measures of psychopathology (GHQ-30: 1.19, 1.07 to 1.31), were more likely to have been abused at a younger age, exposed to the "affectionless control" style of parenting by their mothers, and to have harmed themselves in other ways.

CONCLUSIONS

The management of women presenting to hospital after self-poisoning should include assessment of abuse experiences, and instigation of appropriate treatment in those with significant sequelae of abuse.

The processing of automatic thoughts of drug use and craving in opiate-dependent individuals

This study investigated the processing of sentences describing craving and withdrawal in opiate-dependent individuals. Eighteen patients who attended a methadone maintenance clinic for obtaining methadone, 18 patients who were not treated with methadone, and 18 control family members performed on a computerized contextual priming task. The task was priming sentences (craving, withdrawal, or neutral) to words (addiction, neutral, or nonwords). The methadone group was slower to process all sentences compared with family members. They were also faster to process drug-related words following withdrawal-related sentences compared with neutral words following neutral sentences. Finally, they were slower to recognize neutral words following neutral sentences compared with the nonmethadone group. Results suggest that the processing of information describing withdrawal and craving for drugs plays an important role in opiate dependence.

Physiologically-based pharmacokinetic modeling of pyrene in the rat

The objective of the present study was to develop a physiologically-based model to simulate the oral and i.v. pharmacokinetics of pyrene in the rat. The physiologically-based pharmacokinetic (PBPK) model for pyrene consisted of the following tissue compartments: liver, lungs, adipose tissue, slowly perfused tissues, and richly perfused tissues interconnected with arterial and venous blood pools. The tissue:blood partition coefficients required for the pyrene PBPK model were estimated by equilibrium dialysis. Using perfusion-limited descriptions for tissue uptake and previously determined in vitro-derived hepatic metabolism rate constants (V(max) and K(m)), the PBPK model predicted a faster clearance of pyrene than that suggested by the experimental data. The biological basis of PBPK model then provided an opportunity to refine the estimate of V(max), and to explore and uncover additional mechanistic determinants of pyrene disposition in vivo. Accordingly, the in vitro V(max) had to be lowered by about a factor of 10 to adequately simulate experimental data on pyrene pharmacokinetics. Further, the model simulations could be matched with the experimental data on tissue concentrations of pyrene only with the considerations of (i) diffusion-limited uptake in slowly perfused tissues and adipose tissue, and (ii) binding to proteins in metabolizing tissues (lungs and liver). The present study successfully integrated the available data on oral and i.v. pharmacokinetics of pyrene using a physiological model framework, and identified several mechanistic data gaps that should be addressed by future research efforts.

[Peak bone mass: facts and uncertainties]

Peak bone mass, which can be defined as the amount of bony tissue present at the end of the skeletal maturation, is an important determinant of osteoporotic fracture risk in adulthood. The techniques of single or dual energy absorptiometry measure the so-called "areal" or "surface" bone mineral density (BMD), a variable which has been shown to be directly related to bone strength. During puberty the gender difference in bone mass becomes expressed. This difference appears to be essentially due to a more prolonged bone maturation period in males than in females, with a larger increase in bone size and cortical thickness, as there is no significant sex difference in the volumetric trabecular density at the end of pubertal maturation. At the beginning of the 3rd decade, there is a large variability in the normal values of areal BMD in axial and appendicular skeleton. This large variance, which is observed at sites particularly susceptible to osteoporotic fractures in adulthood, such as lumbar spine and femoral neck, is barely reduced after correction for statural height, and does not appear to substantially increase during adult life. It is generally accepted that peak bone mass at any skeletal site is attained in both sexes during the mid-thirties. However, recent studies indicate that in healthy caucasian females, bone mass accumulation can virtually be completed before the end of the second decade, for both lumbar spine and femoral neck. Several variables are supposed to influence bone mass accumulation during growth: heredity, sex, diet components, endocrine factors, mechanical forces, and exposure to risk factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Transforming growth factor-beta: a down-regulator of the parathyroid hormone-related protein receptor in renal epithelial cells

We have recently provided evidence for the ability of transforming growth factor-beta 1 (TGF beta) to modulate PTH-related protein (PTHrP)-mediated responses in opossum kidney (OK) cells through reducing the number of PTHrP receptor-binding sites. In the present studies, we investigated the possible mechanisms by which TGF beta might regulate PTHrP receptor density in OK cells, an area that has remained largely unexplored. The steady state level of PTHrP receptor mRNA was time dependently reduced by TGF beta treatment, with the nadir (approximately 3-fold decrease) between 6-10 h, preceding the maximal inhibition on PTHrP receptor binding at 18 h. We then assessed whether the 41% reduction in binding consequent to 18-h TGF beta exposure was reversible. PTHrP-binding activity recovered considerably after 24 h (23% decrease compared with controls) and almost completely by 48 h. However, the addition of monensin or cycloheximide, but not actinomycin (at a dose effective in preventing TGF beta action in this system) during the 24-h recovery period prevented restoration of PTHrP binding. Upon removal of TGF beta, the PTHrP receptor message showed a trend toward recovery in the ensuing 24 h. Therefore, TGF beta provides an example of heterologous desensitization of the PTHrP receptor in OK epithelial cells by decreasing the expression of the receptor message. The desensitization was reversible, and the first 24-h recovery phase was dependent on synthesis and processing of new receptor proteins.

Peak bone mass

Peak bone mass, which can be defined as the amount of bony tissue present at the end of the skeletal maturation, is an important determinant of osteoporotic fracture risk. Measurement of bone mass development. The bone mass of a given part of the skeleton is directly dependent upon both its volume or size and the density of the mineralized tissue contained within the periosteal envelope. The techniques of single-1 and dural-energy photon or X-ray absorptiometry measure the so-called 'areal' or 'surface' bone mineral density (BMD), a variable which has been shown to be directly related to bone strength. Bone mass gain during puberty. During puberty the gender difference in bone mass becomes expressed. This difference appears to be essentially due to a more prolonged bone maturation period in males than in females, with a larger increase in bone size and cortical thickness. Puberty affects bone size much more than the volumetric mineral density. There is no significant sex difference in the volumetric trabecular density at the end of pubertal maturation. During puberty, the accumulation rate in areal BMD at both the lumbar spine and femoral neck levels increases to four- to sixfold over a 3- and 4-year period in females and males, respectively. Change in bone mass accumulation rate is less marked in long bone diaphyses. There is an asynchrony between the gain in statural height and bone mass growth. This phenomenon may be responsible for the occurrence of a transient period of a relative increase in bone fragility that may account for the pattern of fracture incidence during adolescence.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of diamond-like carbon coatings on macrophages, fibroblasts and osteoblast-like cells in vitro

The elaboration of metallic and polymeric particles from the wear of joint replacement components is widely implicated in the pathogensis of aseptic loosening of these implants. Diamond-like carbon (DLC) coatings show great potential as wear-retardant coatings and may offer a possible solution to this problem. We have studied the effects of DLC coatings on cells derived from the tissues that surround a total joint replacement (macrophages, fibroblasts and osteoblast-like cells). There was no evidence that DLC coatings, deposited on a variety of different substrates, caused cytotoxicity in vitro. Cells grown on the coated substrates exhibited normal cellular growth and morphology. DLC coatings are biocompatible in vitro and should now be tested in animal models to determine their behaviour in vivo.

Parathyroid hormone-related protein and calcium phosphate metabolism

There is marked homology between the parathyroid hormone (PTH) and PTH-related protein (PTHrP) molecules at the amino terminal but the rest of the molecules are quite different, providing immunologically distinct peptides. However, they interact with the same receptor. Thus, PTHrP mediates biological actions reminiscent of PTH. PTHrP gene is a single copy gene, producing one to three mRNA transcripts through alternative splicing of the carboxy terminal, encoding peptides of 139, 141 or 173 amino acids. Having been recently isolated from malignant tumours, PTHrP is now considered to be the major mediator of humoral hypercalcaemia of malignancy (HHM). The PTH-like effects of PTHrP on the kidney and bone have been well characterized. The increase in renal tubular calcium reabsorption and the reduction in tubular phosphate reabsorption with a concomitant rise in nephrogenous cyclic AMP constitute the pathophysiological changes in the renal handling of calcium and phosphate in HHM. The osteotropic contribution to the malignant hypercalcaemia has been validated by enhanced osteoclastic bone resorption--an indirect effect of the amino terminal portion of the PTHrP molecule on osteoblasts. However, PTHrP has also been detected in a large number of normal adult tissues/organs as well as in human and animal fetuses. Fetal plasma calcium is higher than maternal and this is achieved by active transport of calcium across the placenta. Using ovine placental perfusion models, PTHrP, which is believed to originate from fetal parathyroid glands and the placenta itself, has been demonstrated to sustain this calcium gradient. Active placental transport of magnesium, but not phosphate, was also shown to be enhanced by PTHrP.(ABSTRACT TRUNCATED AT 250 WORDS)

Screening and psychological debriefing of adolescent survivors of life-threatening events

There is a perceived need for schools and casualty departments to receive appropriate information and guidelines in order to minimise the effect of PTSD. A recommended screening battery for PTSD was administered at the start of a two-session debriefing group and again three months later to a group of seven young survivors of a minibus accident. No studies using this screen other than those of shipping disasters have been reported to date. Screen scores were compared with those of survivors of the cruise ship Jupiter. No significant differences were found between minibus survivors when assessed at six months (before intervention), and Jupiter survivors, who when assessed at five months had already undergone debriefing. Post-debriefing assessment of minibus survivors demonstrated significant reductions on all measures.

Transforming growth factor-beta modulates the parathyroid hormone-related protein-induced responses in renal epithelial cells

PTH-related protein (PTHrP), the major mediator of hypercalcemia of malignancy, reduces tubular phosphate (Pi) reabsorption through its PTH-like renotropic actions. Another peptide detected in tumoral cells, transforming growth factor-beta (TGF beta), has been shown to considerably suppress the sodium-dependent Pi transport system present in the apical membrane of renal epithelial cells. The unexplored interactions between TGF beta and PTHrP were examined in opossum kidney (OK) cells. Using confluent OK cells, we showed that TGF beta attenuated the inhibition of Pi transport mediated by PTHrP. Similarly, 18 h TGF beta incubation resulted in a substantial reduction of the cAMP response elicited by PTHrP without apparent involvement of pertussis toxin-sensitive guanine nucleotide binding protein(s). The number of PTHrP(1-34) binding sites in TGF beta-treated cells was decreased with the affinity unchanged. Forskolin- and prostaglandin E2-stimulated cAMP productions were not significantly altered by TGF beta treatment. Therefore, TGF beta reduced Pi transport in OK cells, modulated the actions of PTHrP, and decreased its receptor number. Whether this happens in vivo is as yet unknown.

Transforming growth factor-beta inhibits phosphate transport in renal epithelial cells

The effect(s) of transforming growth factor-beta (TGF-beta) on Pi transport was investigated in confluent opossum kidney (OK) epithelial cells. TGF-beta induced a time- and concentration-dependent decrease in the initial rate of sodium-dependent Pi, but not alanine, transport. This selective inhibitory effect on Pi transport was largely reversible and was not associated with a rise in adenosine 3',5'-cyclic monophosphate production. The reduction in Pi uptake was also independent of changes in extracellular calcium concentrations and prostaglandin synthesis. TGF-beta-mediated Pi transport inhibition appeared to involve neither pertussis toxin-sensitive G protein(s) nor augmented protein kinase C activity. However, the probable role of a serine/threonine protein kinase in signal transduction was supported by the considerable attenuation of TGF-beta effect by H-7. Furthermore, the TGF-beta-induced Pi transport reduction was blunted by cycloheximide and abolished by actinomycin D. In conclusion, TGF-beta selectively inhibits the activity of the sodium-dependent Pi transport system present in the apical membrane of renal epithelial cells. This action appears to be exerted via an unprecedented inhibitory pathway that might involve a serine/threonine protein kinase and alterations in the transcriptional and translational processes.

Failure of intraventricular gammaglobulin and alpha interferon for persistent encephalitis in congenital hypogammaglobulinaemia

A boy with congenital hypogammaglobulinaemia died at the age of 12 years after a viral meningoencephalitis of two and a half years duration due to an untypable picornavirus. He had received intravenous immunoglobulin every four weeks from the time of the start of immunoglobulin replacement treatment at the age of 3 years. The encephalitis did not respond to high dose intravenous gammaglobulin (2500 g during 22 months). The virus could not be isolated during the administration of intraventricular immunoglobulin (38.15 g) and intraventricular recombinant alpha interferon (121 X 10(6) units), but recurred rapidly each time intraventricular treatment was stopped. Further modes of treatment are still required for prevention and treatment of this disorder.

Toxicokinetics and bioavailability of paraquat in rats following different routes of administration

The toxicokinetics and bioavailability of [14C]paraquat were examined in rats which had received a single dose (11.6 micrograms/kg) of the herbicide by the iv, intragastric, dermal or pulmonary route. In the pulmonary route studies, rats were exposed to an aqueous solution or liquid aerosols of [14C]paraquat through a tracheal cannula or [14C]paraquat aerosols in a nose-only inhalation chamber. After intratracheal, intragastric, and dermal administration of [14C]paraquat to the rat, the average bioavailabilities were 0.45 +/- 0.22, 0.12 +/- 0.03, and 0.038 +/- 0.027, which corresponded to 20.3 nmol, 5.4 nmol and 1.7 nmol of [14C]paraquat, respectively. Since the dose administered to the rat in the [14C]paraquat aerosol studies was unknown, the bioavailability for this exposure route could not be determined. However, about 27.5 nmol of [14C]paraquat was observed into the systemic circulation of the rat after inhaling [14C]paraquat aerosols through a tracheal cannula. [14C]paraquat administered to the rat iv was eliminated from the blood with a half-life of about 68 min. Urine and feces were the major excretion routes. The radioactivity absorbed into the systemic circulation of the rat was approximately equal to that excreted in the urine; about 23.8 nmol, 8.5 nmol and 1.5 nmol of [14C]paraquat were recovered from the urine of the rat after inhalation of [14C]paraquat aerosols in a nose-only exposure chamber, intragastric injection and dermal absorption of [14C]paraquat, respectively. Tissue distribution studies showed that the bulk of the [14C]paraquat administered to the rat by the inhalation and dermal routes remained at the sites of administration.