The potential of ketamine for posttraumatic stress disorder: a review of clinical evidence

Posttraumatic stress disorder (PTSD) is a devastating condition, for which there are few pharmacological agents, often with a delayed onset of action and poor efficacy. Trauma-focused psychotherapies are further limited by few trained providers and low patient engagement. This frequently results in disease chronicity as well as psychiatric and medical comorbidity, with considerable negative impact on quality of life. As such, off-label interventions are commonly used for PTSD, particularly in chronic refractory cases. Ketamine, an N-methyl-D-aspartate (NDMA) receptor antagonist, has recently been indicated for major depression, exhibiting rapid and robust antidepressant effects. It also shows transdiagnostic potential for an array of psychiatric disorders. Here, we synthesize clinical evidence on ketamine in PTSD, spanning case reports, chart reviews, open-label studies, and randomized trials. Overall, there is high heterogeneity in clinical presentation and pharmacological approach, yet encouraging signals of therapeutic safety, efficacy, and durability. Avenues for future research are discussed.

Prefrontal Glutamate Neurotransmission in PTSD: A Novel Approach to Estimate Synaptic Strength in Vivo in Humans

Background

Trauma and chronic stress are believed to induce and exacerbate psychopathology by disrupting glutamate synaptic strength. However, in vivo in human methods to estimate synaptic strength are limited. In this study, we established a novel putative biomarker of glutamatergic synaptic strength, termed energy-per-cycle (EPC). Then, we used EPC to investigate the role of prefrontal neurotransmission in trauma-related psychopathology.

Methods

Healthy controls (n = 18) and patients with posttraumatic stress (PTSD; n = 16) completed ¹³C-acetate magnetic resonance spectroscopy (MRS) scans to estimate prefrontal EPC, which is the ratio of neuronal energetic needs per glutamate neurotransmission cycle (V_TCA/V_Cycle).

Results

Patients with PTSD were found to have 28% reduction in prefrontal EPC (t = 3.0; df = 32, P = .005). There was no effect of sex on EPC, but age was negatively associated with prefrontal EPC across groups (r = -0.46, n = 34, P = .006). Controlling for age did not affect the study results.

Conclusion

The feasibility and utility of estimating prefrontal EPC using ¹³C-acetate MRS were established. Patients with PTSD were found to have reduced prefrontal glutamatergic synaptic strength. These findings suggest that reduced glutamatergic synaptic strength may contribute to the pathophysiology of PTSD and could be targeted by new treatments.

Pretreatment Brain Connectome Fingerprint Predicts Treatment Response in Major Depressive Disorder

Background

Major depressive disorder (MDD) treatment is characterized by low remission rate and often involves weeks to months of treatment. Identification of pretreatment biomarkers of response may play a critical role in novel drug development, in enhanced prognostic predictions, and perhaps in providing more personalized medicine. Using a network restricted strength predictive modeling (NRS-PM) approach, the goal of the current study was to identify pretreatment functional connectome fingerprints (CFPs) that (1) predict symptom improvement regardless of treatment modality and (2) predict treatment specific improvement.

Methods

Functional magnetic resonance imaging and behavioral data from unmedicated patients with MDD (n = 200) were investigated. Participants were randomized to daily treatment of sertraline or placebo for 8 weeks. NRS-PM with 1000 iterations of 10 cross-validation were implemented to identify brain connectivity signatures that predict percent improvement in depression severity at week-8.

Results

The study identified a pretreatment CFP that significantly predicts symptom improvement independent of treatment modality but failed to identify a treatment specific CFP. Regardless of treatment modality, improved antidepressant response was predicted by high pretreatment connectivity between modules in the default mode network and the rest of the brain, but low external connectivity in the executive network. Moreover, high pretreatment internal nodal connectivity in the bilateral caudate predicted better response.

Conclusions

The identified CFP may contribute to drug development and ultimately to enhanced prognostic predictions. However, the results do not assist with providing personalized medicine, as pretreatment functional connectivity failed to predict treatment specific response.

A Unique Brain Connectome Fingerprint Predates and Predicts Response to Antidepressants

More than six decades have passed since the discovery of monoaminergic antidepressants. Yet, it remains a mystery why these drugs take weeks to months to achieve therapeutic effects, although their monoaminergic actions are present rapidly after treatment. In an attempt to solve this mystery, rather than studying the acute neurochemical effects of antidepressants, here we propose focusing on the early changes in the brain functional connectome using traditional statistics and machine learning approaches. Capitalizing on three independent datasets (n = 1,261) and recent developments in data and network science, we identified a specific connectome fingerprint that predates and predicts response to monoaminergic antidepressants. The discovered fingerprint appears to generalize to antidepressants with differing mechanism of action. We also established a consensus whole-brain hierarchical connectivity architecture and provided a set of model-based features engineering approaches suitable for identifying connectomic signatures of brain function in health and disease.

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Machine learning methods were used to fully investigate the brain connectome

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Network-informed features engineering approaches were proposed

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A cortical-subcortical hierarchical brain atlas was established

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A specific connectome signature was found to predict response to antidepressants

The Toronto Western Hospital Catheter: One Center's Experience and Review of the Literature

Background

We report our center's experience with the Toronto Western Hospital (TWH) catheter, and discuss our catheter survival and complication rates.

Methods

Retrospective chart review of patients receiving peritoneal dialysis therapy via a TWH catheter. Catheter complication rates of peritonitis, exit site infection, obstruction, leak, and malfunction were assessed. A catheter was considered failed if removed because of exit site infection, obstruction, or malfunction. All other catheters, even if removed for other reasons, were considered censured. Survival was defined as the period from insertion to failure or censure date, and reported using Kaplan Meier analysis.

Results

192 patients with a total of 208 TWH catheters (4,845.3 catheter months) were analyzed. Our overall 1- and 3-year catheter survival rates were identical at 0.9182. Our catheter complication rates (expressed as number of catheter months per event) were 31.3 for peritonitis, 42.9 for exit site infection, 72.3 for obstruction, 538.4 for malfunction, and 969.1 for catheter leak. Our findings were similar to those reported in the literature for TWH and other peritoneal catheters.

Abstract P3-09-02: Optimal anti-emetic choice for breast cancer patients receiving anthracycline and cyclophosphamide-based chemotherapy - A systematic review and network meta-analysis of randomized controlled trials

Background: International expert consensus groups such as ASCO (JCO 2011) and MASCC (Ann of Oncol. 2010) recommend that patients (pts) receiving anthracycline and cyclophosphamide-based chemotherapy (A&C-CT) regimens receive an anti-emetic combination of 5HT3 antagonist (day 1), NK1 receptor antagonist (day/s 1 or 1-3), and dexamethasone (days 1-3/4). Clinical experience would suggest that Total Control (no episodes of chemotherapy-induced nausea and vomiting [CINV] and no rescue anti-emetic use for 5 days after CT) is often not achieved. We therefore sought to use Network meta-analysis (NMA) to provide a quantitative summary of existing randomised controlled trials (RCTs) to identify the optimal anti-emetic regimen for these pts.

Methods: A peer reviewed search of RCTs assessing combination anti-emetic regimens in breast cancer pts on A&C-CT was performed using Medline, Embase and Cochrane CENTRAL. No additional restriction criteria were employed. Two individuals independently screened citations and full text articles to identify eligible RCTs. Pt and study characteristics, as well as, outcome data were collected to ensure studies were sufficiently similar to include in the NMA. The primary outcome was Total Control of CINV (no nausea, no vomiting, and no rescue anti-emetics for 5 days). Secondary outcomes included Complete Response (no vomiting and no rescue medications for 5 days), No Vomiting and No Nausea in the acute (0-24 hrs) and delayed (24-120 hrs) periods, respectively.

Results: From 962 citations identified, 152 were retained after abstract screening, and 20 retained after full-text screening. Trials were published from 1990 to 2012. There was limited reporting of pt characteristics and CINV outcomes beyond the first CT cycle. The majority of comparisons in the network of treatments were supported by only one RCT. The significant heterogeneity in anti-emetic regimens (n = 21) mandated combining treatment doses and durations to make NMA feasible. Six out of 20 studies reported Total Control, occurring in a mean proportion of 26.9% (23 - 65%) of pts. Complete Response was reported in 11/18 trials, occurring in a mean of 49.8% (31.2% - 79.3%) of pts.

Conclusions: Clinical experience suggests that despite best practice recommendations, many pts do not achieve Total Control of CINV. In preparing for a NMA, we identified marked heterogeneity between trials. This included variability in study design, sample size, treatment agents, duration of agents used, and in reporting of pt characteristics and outcome measures. Given these limitations, despite the recommendations of consensus groups, we have yet been able to make any firm decision on the optimal anti-emetic regimen based on the evidence at this time. We will present findings from our NMA, which will try to account for these limitations. However, if anti-emetic care is to be improved future pragmatic RCTs that include both nausea and vomiting outcomes are clearly required.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-09-02.

Oral health awareness and care preferences in patients with diabetes: a qualitative study

BACKGROUND

People with type 2 diabetes have an increased risk of oral health problems; however, oral health is currently not included in structured diabetes reviews and education in the UK.

AIM AND OBJECTIVES

This study explores the patient's experience related to oral health and diabetes, especially in relation to: • Awareness of the link between oral health and diabetes and oral self-care needs. • Interaction with health professionals in dental and general practice. • Preferences for receiving oral health information and education. Methods This nested qualitative study involved semi-structured telephone interviews with a purposive sample of 20 participants from a questionnaire study on oral health awareness in patients with diabetes. Interview transcripts were analysed using a thematic framework approach.

RESULTS

Participants were mostly unaware of the link between oral health and diabetes. Those that had been made aware by a health professional were not given concrete self-care advice. Interactions with dental professionals were often limited to informing the dental practice of their diagnosis and current medication. Most participants were in favour of dentists screening for diabetes, but as their general practice was the hub for diabetes care, they felt GPs or nurses should provide oral health information and discuss oral health with patients.

CONCLUSIONS

Written information regarding diabetes and its possible effects on oral health needs to be more readily available to people with diabetes, especially at diagnosis. There may be a place for introducing a structured oral health question in routine diabetes reviews.

First Report of Soybean Rust Caused by Phakopsora pachyrhizi on Pachyrhizus erosus in the United States

Soybean rust, caused by the fungus Phakopsora pachyrhizi, was detected on jicama (Pachyrhizus erosus L. Urban) for the first time in the United States in November 2009. The pathogen was observed on leaves of a single, potted jicama plant grown outdoors in a residential area and on leaves of all plants in a 12-m² demonstration plot located at the Auburn University Teaching Garden in Auburn, AL. Symptoms on the upper leaf surfaces were isolated chlorotic areas near the leaf edges in the lower part of the canopy. The abaxial surface was first observed to exhibit brown lesions and subsequently produced volcano-shaped uredinia. These symptoms are consistent with a rust previously described on jicama in Mexico (1). Representative symptomatic plant tissue was sent to the USDA National Identification Services (Mycology) Laboratory in Beltsville, MD for diagnostic confirmation at both the Urbana, IL lab and the USDA National Plant Germplasm and Biotechnology Laboratory for DNA testing. From an infected leaf, samples of approximately 5 mm² were excised from a microscopically observed rust lesion and an apparently noninfected area. Total DNA was purified with the FastDNA Spin Kit (MP Biomedicals, Solon, OH) followed by the E.Z.N.A. MicroElute DNA Clean-Up Kit (Omega Bio-tek, Inc, Doraville, GA) per manufacturer's instructions. Detection of P. pachyrhizi and P. meibomiae DNA was achieved by quantitative PCR using the method of Frederick et al. (2) and a DNA standard of previously prepared P. pachyrhizi spores. The observed rust pustule was found to contain P. pachyrhizi DNA in excess of 28,000 genomes, while no P. pachyrhizi DNA was observed from the asymptomatic sample. Both samples were negative for P. meibomiae. The fungal structures present were confirmed to be Phakopsora spp. DNA was extracted from sori aseptically removed from leaves with a Qiagen (Valencia, CA) DNeasy Plant Mini Kit and amplified with primers Ppa1 and NL4. The resulting partial ITS2 and 28S ribosomal RNA sequences were 100% identical to GenBank entry DQ354537 P. pachyrhizi internal transcribed spacer 2 and 28S ribosomal RNA gene, partial sequence. Sequences from jicama from Alabama were deposited in GenBank. Voucher specimens were deposited in the USDA Agricultural Research Service, National Fungus Collection (BPI). To our knowledge, this is the first report of the disease on jicama in the United States. References: (1) A. Cárcamo Rodriguez et al. Plant Dis. 90:1260, 2006. (2) R. D. Frederick et al. Phytopathology 92:217, 2002.

Expression of Inflammatory Molecules Among Breast Cancer Patients Receiving Different Chemotherapies:Implications for Chemobrain

Increased levels of MCP-1, IL-8 and IL-6 are associated with mild cognitive impairment, defined as frequent and irregular bouts of forgetfulness, difficulties with attention and/or difficulties with language-a condition with comparable symptomology reported by cancer patients experiencing chemobrain. High levels of these molecules may compromise neuronal and synaptic integrity, leading to cognitive impairment. Patients receiving doxorubicin-based (with cyclophosphamide, or cyclophosphamide and fluorouracil; AC/CAF) chemotherapy or a combination of cyclophosphamide, methotrexate, and fluorouracil (CMF) chemotherapy report experiencing chemobrain, but MCP-1, IL-8 and IL-6 may be differentially influenced by these regimens. The purpose of this study was to examine changes in expression of these molecules among breast cancer patients (N = 54) receiving combinations of AC/CAF or CMF. Changes in MCP-1, IL-8 and IL-6 were assessed at baseline (T1) and after 2 chemotherapy cycles (T2). T-tests were used to compare between group and within group differences on raw means and mean change (T2-T1). IL-6 significantly increased in the AC/CAF group (4.95 pg/mL,SEM = 2.31;P < 0.05), but MCP-1 (42.8 pg/mL;SEM = 40.36) and IL-8 (0.25 pg/mL;SEM = 1.19) did not. IL-6 (−1.46 pg/mL,SEM = 0.94), MCP-1 (−15.8 pg/mL,SEM = 49.95) and IL-8 (−0.79 pg/mL,SEM = 1.04) all decreased in the CMF group; however, none of these changes were significant. No significant differences in IL-6 (1.06 pg/mL, SEM = 1.05), MCP-1(73.48 pg/mL, SEM = 67.30), or IL-8 (−1.95 pg/mL, SEM = 3.28) at T1 were observed between AC/CAF and CMF groups. At T2, there was a significant difference in IL-6 (7.72 pg/mL,SEM = 3.82; P ≤ 0.05) between AC/CAF and CMF groups, but not in MCP-1 (131.91 pg/mL,SEM = 87.09) or IL-8 (5.72 pg/mL,SEM = 4.0). A significant change (T2-T1) in IL-6 (6.41 pg/mL,SEM = 2.57;P < 0.05) between AC/CAF and CMF groups was observed. Changes in MCP-1 (58.65 pg/mL,SEM = 63.94) and IL-8 (1.08 pg/mL,SEM = 1.58) between groups were not significant. These results suggest AC/CAF and CMF chemotherapy regimens elicit distinct inflammatory response patterns in MCP-1, IL-8 and IL-6 suggesting different mechanisms may be responsible for the development of chemobrain. Future research is needed to confirm these findings. Funding:NCI R25CA10618.

Prevalence and severity of sleep disturbance in 596 cancer patients: A URCC CCOP study

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Background: Sleep disturbance is a prevalent and, potentially, chronic problem among cancer patients, persisting for many months and years after treatments. As part of a multi-center longitudinal survey of patients beginning cancer treatments, we prospectively investigated the prevalence and severity of self-reported sleep disturbance. Methods: 596 Cancer patients (mean age=61; 66.4%=female) receiving chemotherapy and/or radiation (37.1%=chemotherapy, 40.1%=radiation therapy, 22.8%=both) from 17 NCI CCOPs reported whether they experienced any sleep disturbance using an 11-point Likert Scale (0 = “Not present” to 10 = “As bad as you can imagine”) prior to treatments, during treatments, and 6 months after finishing treatments. A side effect level 7 was considered “severe.” Results: Sleep disruption was reported by 31.9% (median=2; 10.6% severe) at baseline, 77.2% (median=4; 28.5% severe) during treatment and 65.1% (median=2; 15% severe) at 6 months post-treatment. Repeated-measures ANOVAs revealed statistically significant treatment group (chemotherapy, radiation, or both), age (< 61 or ≥ 61 yrs), and gender by time interactions (all p<0.05). Sleep disturbance was significantly higher among survivors in the two groups receiving chemotherapy, younger survivors, and women (all p<0.05). Sleep disruption increased from baseline to post-treatment and decreased from post-treatment to 6 months post-treatment (all p<0.05). There were no significant differences between baseline and 6 months post-treatment. Conclusions: These results show that difficulties with sleep increase during cancer treatment. Patients who are at higher risk for having sleep problems are women, younger patients, and patients undergoing chemotherapy. Supported by NCI Grants U10-CA37420 and R25-CA102618

No significant financial relationships to disclose.

Symptom interval in young people with bone cancer

Symptom interval (SI), the time from first symptom/sign to diagnosis and initiation of treatment, appears to be principally influenced by tumour biology. Whether the age of the patient, patient delay, professional delay and access to health professionals influences the SI in bone tumours was investigated in this study. 115 patients with newly diagnosed osteosarcoma and Ewing's sarcoma were retrospectively reviewed. The median total SI for all bone tumours was 3.8 months (range 1-46 months). Patients older than 12 years had a longer SI (P = 0.05) and more patient delays (P = 0.02). Total SI and professional delays were longer if the General Practitioner was first seen compared with an Accident and Emergency Consultant (P = 0.02 and 0.02, respectively). However, SI did not influence overall and event-free survival in this series. Bone tumour patients have long SIs that are significantly affected by age and local health-care support systems. Early referral to specialists would help to alleviate anxiety and distress to the patient and family, even if currently delay does not influence outcome.

Chronic peritoneal dialysis in octogenarians

BACKGROUND

During the past few decades the pattern of end-stage renal failure disease has changed with increasing number of elderly patients admitted for dialysis. In spite of their increasing number, little is known about the optimal mode of therapy of the 'old old' (those >or=80 years) patients.

METHODS

In this retrospective study, we analysed the results of treatment of 31 non-institutionalized 'old old' patients at Toronto Western Hospital (17) and Scarborough General Hospital (14) and seven institutionalized patients in chronic care, Riverdale Hospital. The patients were on CAPD with Twin-bag Baxter (28) or Home Choice, Baxter or Fresenius CCPD system (10). Patients were screened at the CAPD clinic when routine blood investigations were done. Patient and technique survival, initial and final laboratory data (last visit or before death) and complications related/unrelated to dialysis method are presented.

RESULTS

Multiple comorbid conditions were present at the start of the treatment and new added during treatment; very few were dialysis-related. The majority of non-institutionalized patients required assistance of home-care nurse to perform dialysis. Peritonitis (1/28.6 patient months) and exit-site infection rate (1/75.1 patient months) were low and responded to treatment. Incidence of peritonitis was higher among institutionalized debilitated patients (1/5.3 patient months). Incidence of hospitalization was 1/14.7 patient months and patients spent in hospital 7.5 days/patient year. Forty-seven per cent of patients survived 24 months; 39% survived 30 months. Technique survival was 91.5% at 12 months and 81.4% at 30 months. Poor appetite and malnutrition were frequent among very old patients. Patients and their families were motivated for treatment and discontinuation of dialysis was not higher than described elsewhere in literature.

CONCLUSIONS

This study has demonstrated that chronic peritoneal dialysis could be recommended as a safe and suitable modality of treatment of end-stage renal failure in old old patients.

Malignant gliomas display altered pH regulation by NHE1 compared with nontransformed astrocytes

Malignant gliomas exhibit alkaline intracellular pH (pH(i)) and acidic extracellular pH (pH(e)) compared with nontransformed astrocytes, despite increased metabolic H(+) production. The acidic pH(e) limits the availability of HCO(-)(3), thereby reducing both passive and dynamic HCO(-)(3)-dependent buffering. This implies that gliomas are dependent upon dynamic HCO(-)(3)-independent H(+) buffering pathways such as the type 1 Na(+)/H(+) exchanger (NHE1). In this study, four rapidly proliferating gliomas exhibited significantly more alkaline steady-state pH(i) (pH(i) = 7.31-7.48) than normal astrocytes (pH(i) = 6.98), and increased rates of recovery from acidification, under nominally CO(2)/HCO(-)(3)-free conditions. Inhibition of NHE1 in the absence of CO(2)/HCO(-)(3) resulted in pronounced acidification of gliomas, whereas normal astrocytes were unaffected. When suspended in CO(2)/HCO(-)(3) medium astrocyte pH(i) increased, yet glioma pH(i) unexpectedly acidified, suggesting the presence of an HCO(-)(3)-dependent acid loading pathway. Nucleotide sequencing of NHE1 cDNA from the gliomas demonstrated that genetic alterations were not responsible for this altered NHE1 function. The data suggest that NHE1 activity is significantly elevated in gliomas and may provide a useful target for the development of tumor-selective therapies.

Is peritoneal dialysis a good option for black patients?

Blacks are less likely than whites to use peritoneal dialysis (PD) as the initial renal replacement therapy. The reason for the underusage of PD by blacks is unknown. In a cross-sectional multicenter trial, we studied peritoneal transport character, small-molecular-weight solute clearances, and nutritional status in 475 patients undergoing PD (168 whites, 192 blacks, and 115 Asians). The mean age of blacks undergoing PD was significantly younger than that of whites (47.6 +/- 14.7 v 58.2 +/- 16.7 years; P < 0.0001). Target Kt/V and weekly creatinine clearance (WCC) as defined by the Dialysis Outcome Quality Initiative Work Group was achieved by 62.5% of whites, 67.2% of blacks, and 54.8% of Asians (P = 0.05). Total protein (7.25 +/- 0.88 v 6.55 +/- 0.73 g/dL), albumin (3.72 +/- 0.57 v 3.55 +/- 0.53 g/dL), and lean body mass (LBM; 41.7 +/- 15.6 v 33.0 +/- 11.8 kg) were lower in whites compared with blacks (P < 0.001). Although the normalized protein catabolic rate (nPCR) was greater (0.82 +/- 0.24 v 0.90 +/- 0.32 g/kg/d; P = 0.04), total protein (6.24 +/- 0.85 g/dL) and serum albumin levels (3.36 +/- 0.52 g/dL) and LBM (30.1 +/- 8.0 kg) were significantly lower in Asians than blacks (P < 0.0001). The favorable anabolic response in blacks may partially be explained by a higher calorie intake in this group of patients (29.6 +/- 10.7 Cal/kg/d) compared with whites (22.4 +/- 6.8 Cal/kg/d) and Asians (23.9 +/- 9.8 Cal/kg/d; P = 0.03). Multiple regression analysis identified that black race and weight were positively associated, whereas dialysate/plasma creatinine ratio (D/P(Creat)) and age had a negative effect on serum albumin level. Follow-up data indicated that the Kt/V (2.09 +/- 0.50 v 2.39 +/- 0.56; P = 0.02) and WCC (60.8 +/- 4.3 v 70.2 +/- 7.3 L/1.73 m2; P = 0.02) increased significantly from baseline only in blacks. We conclude that PD is an ideal renal replacement therapy in at least a subset of blacks with end-stage renal disease.

Feasibility of an airborne TV camera as a size spectrometer for cloud droplets in daylight

Photographs of clouds taken with a camera with a large aperture ratio must have a short depth of focus to resolve small droplets. Hence the sampling volume is small, which limits the number of droplets and gives rise to a large statistical error on the number counted. However, useful signals can be obtained with a small aperture ratio, which allows for a sample volume large enough for counting cloud droplets at aircraft speeds with useful spatial resolution. The signal is sufficient to discriminate against noise from a sunlit cloud as background, provided the bandwidth of the light source and camera are restricted, and against readout noise. Hence, in principle, an instrument to sample the size distribution of cloud droplets from aircraft in daylight can be constructed from a simple TV camera and an array of laser diodes, without any components or screens external to the aircraft window.

A spectrum of mutations in the polycystic kidney disease-2 (PKD2) gene from eight Canadian kindreds

Autosomal dominant polycystic kidney disease (ADPKD) is a common Mendelian disorder that affects approximately 1 in 1000 live births. Linkage studies have shown that the majority (approximately 85%) of cases are due to mutations in PKD1 on chromosome 16p, while mutations in PKD2 on chromosome 4q account for most of the remaining cases. Locus heterogeneity in ADPKD is known to contribute to differences in disease severity, with PKD1-linked families having earlier onset of end-stage renal disease (ESRD) than PKD2-linked families (mean age at ESRD: 56 versus 70, respectively). In this study, 11 Canadian families with ADPKD were screened for PKD2 mutations. In four families, linkage to PKD2 was previously documented. In the remaining seven smaller families, one or more affected members had late-onset ESRD at age 70 or older. Using single-stranded conformational polymorphism analysis, one affected member from each family was screened for mutations in all 15 exons of PKD2, which were PCR-amplified from genomic templates. A spectrum of mutations was found in approximately 73% (8 of 11) of the families screened, with no difference in the detection rate between the PKD2-linked families and the families with late-onset ESRD. In three unrelated families, insertion or deletion of an adenosine in a polyadenosine tract (i.e., (A)8 at nt 2152-2159) was found on exon 11, suggesting that this mononucleotide repeat tract is prone to mutations from "slipped strand mispairing." All mutations, scattered between exons 1 and 11, are predicted to result in a truncated polycystin 2 that lacks both the calcium-binding EF-hand domain and the two cytoplasmic domains required for the interaction of polycystin 2 with polycystin 1 and with itself. Furthermore, no correlation was found between the location of the mutations in the PKD2 coding sequence and disease severity. Thus, these findings are consistent with other recently published reports and suggest that most PKD2 mutations are inactivating.

Ethnic variability in peritoneal equilibration test and urea kinetics

The influence of ethnicity on peritoneal permeability and the adequacy of peritoneal dialysis was studied in 202 end-stage renal failure patients on peritoneal dialysis. Patients were classified into whites, Orientals, blacks, and a miscellaneous group consisting of East Indians, Persians, and others whose ethnicity was unknown. The patients were on peritoneal dialysis for a mean period of 29.1 +/- 15.8 months before the study. All patients underwent a peritoneal equilibration test with 24-hour urine and dialysate collection. The kinetic parameters were calculated using commercial software (PD Adequest; Baxter Healthcare, Round Lake, IL). The mean volume of exchange, weekly Kt/V, and weekly creatinine clearance were comparable in the different ethnic groups, but the normalized protein catabolic rate was significantly higher in the Orientals (P = 0.03). The high transporters tended to be males with a large body surface area and in the older age group. The low transporters achieved a higher Kt/V than those in the other transport groups (2.3 +/- 0.4 v 2.06 +/- 0.52; P = 0.015). The women had a significantly higher Kt/V than the men (2.16 +/- 0.43 v 1.93 +/- 0.59; P < 0.01). Repeat peritoneal equilibration test was done after a mean duration of 10.5 +/- 4.9 months in 33 patients. Although the mean exchange volume (8.37 +/- 0.83 v 9.32 +/- 1.72; P = 0.003) increased significantly, weekly creatinine clearance (62.3 +/- 25.6 L/1.73 m2 to 63.1 +/- 18.3 L/1.73 m2; P < 0.05) and other kinetic parameters did not change markedly with duration. There was a tendency for the patients to move from the extreme transport groups to the average category with duration.

Development of a Synthetic Route to Unsymmetrical Triphosphine Ligands and an Investigation of Their Coordination Chemistry with Nickel and Palladium

Chiral tridentate phosphines, R(2)P(CH(2))(3)PPh(CH(2))(2)PPh(2) where R = C(6)H(5), p-ClC(6)H(4), and p-FC(6)H(4), can be prepared from simple starting materials, (R(3)P, I(CH(2))(3)I, and Ph(2)P(CH(2))(2)PPh(2)), in a few stages involving phosphonium salts and phosphine oxides as intermediates. Crystalline diamagnetic complexes of nickel(II) and palladium(II) have been isolated. In solution these show first-order 12 line (31)P NMR spectra consistent with three nonequivalent phosphorus nuclei coupled to one another in a square planar geometry. A single X-ray crystallographic study of NiI(2){P(CH(2))(3)PPh(CH(2))(2)PPh(2)} showed that this was square pyramidal in the solid state with a weakly held apical iodo ligand.

A randomized controlled trial of prednisone in patients with idiopathic membranous nephropathy

We conducted a prospective randomized study in which patients with biopsy-confirmed idiopathic membranous nephropathy were assigned to receive either a six-month course of prednisone given on alternate days (45 mg per square meter of body-surface area; n = 81) or no specific treatment (n = 77). The mean duration of follow-up was 48 months. Patients in the prednisone group (median age, 46 years) entered with a mean disease duration of 15 months, a median creatinine clearance of 1.2 ml per second per 1.73 m2 (range, 0.25 to 2.6), and a median rate of urinary protein excretion of 6.8 g per day (0.3 to 26). The annual change in the corrected creatinine clearance at six months did not differ between the prednisone group and the control group (0.10 vs. 0.06 ml per second; P = 0.8), or at the last follow-up evaluation (-0.07 vs. -0.02 ml per second; P = 0.2; 95 percent confidence interval on the difference, -0.03 to 0.13). The proportion of patients with complete remission of proteinuria was also similar in the groups at 6 and 12 months and after a mean of 48 months. Outcomes were similar in the two groups with respect to progression to renal failure (3 vs. 4 patients), death (3 vs. 1 patient), complete remission of proteinuria at 36 months (16 vs. 19 patients), and a decline of 25 percent or more in the creatinine clearance at 60 months (32 vs. 25 percent of patients). A multivariate analysis, which adjusted for differences at entry in sex distribution, urinary protein excretion, and creatinine concentration, as well as other prognostic variables, failed to provide an explanation for the lack of effect of prednisone. We conclude that a six-month course of therapy in which prednisone is given on alternate days is of no benefit to patients with idiopathic membranous nephropathy.

Plasmapheresis and antiplatelet agents in the treatment of the hemolytic uremic syndrome secondary to mitomycin

Four patients with the hemolytic uremic syndrome secondary to mitomycin therapy were treated with intense plasmapheresis and antiplatelet agents. All four patients had a hematologic response and three had slow, but steady, improvement in renal function. These results suggest an important role for these agents in mitomycin-induced hemolytic uremic syndrome.

Experiments relating to the biosynthesis of bacilysin

1. Bacilysin, a peptide which yields l-alanine and l-tyrosine on acid hydrolysis, was produced by a strain of Bacillus subtilis (A 14) in a chemically defined medium containing glucose, ammonium acetate or ammonium chloride, potassium phosphate and other inorganic salts, and ferric citrate. 2. Under the conditions used growth was diphasic. Bacilysin was formed during the second phase of slower growth, and there was little production during the stationary phase. Nevertheless, bacilysin production occurred when protein synthesis was inhibited by chloramphenicol. It thus appears that there is no obligatory coupling of protein synthesis and bacilysin synthesis. 3. When dl-[1-(14)C]alanine was added to a growing culture of B. subtilis, (14)C was incorporated into bacilysin, which contains an N-terminal alanine residue. 4. Under similar conditions virtually no (14)C was incorporated into bacilysin from dl-[2-(14)C]tyrosine, l-[U-(14)C]tyrosine or [1-(14)C]acetate, although these compounds were used by the cell for the biosynthesis of other substances. These results indicate that neither tyrosine nor acetate is a precursor of the fragment of bacilysin which yields tyrosine on hydrolysis with hot 6n-hydrochloric acid. 5. The tyrosine-yielding fragment of bacilysin was labelled with (14)C from [1,6-ring-(14)C(2)]shikimic acid. The biosynthesis of bacilysin thus appears to involve a diversion from the pathway leading to aromatic amino acids at the shikimic acid stage, or a subsequent one.