MSH-MLH complexes formed at a DNA mismatch are disrupted by the PCNA sliding clamp

In the yeast Saccharomyces cerevisiae, mismatch repair (MMR) is initiated by the binding of heterodimeric MutS homolog (MSH) complexes to mismatches that include single nucleotide and loop insertion/deletion mispairs. In in vitro experiments, the mismatch binding specificity of the MSH2-MSH6 heterodimer is eliminated if ATP is present. However, addition of the MutL homolog complex MLH1-PMS1 to binding reactions containing MSH2-MSH6, ATP, and mismatched substrate results in the formation of a stable ternary complex. The stability of this complex suggests that it represents an intermediate in MMR that is subsequently acted upon by other MMR factors. In support of this idea, we found that the replication processivity factor proliferating cell nuclear antigen (PCNA), which plays a critical role in MMR at step(s) prior to DNA resynthesis, disrupted preformed ternary complexes. These observations, in conjunction with experiments performed with streptavidin end-blocked mismatch substrates, suggested that PCNA interacts with an MSH-MLH complex formed on DNA mispairs.

The pitfalls of transthoracic echocardiography. A case of eustachian valve endocarditis

A case of infective endocarditis involving the vestigial eustachian valve is presented and the available English medical literature is reviewed. Only 5 prior cases have been reported: 4 of those required transesophageal echocardiography for diagnosis, and the other was found at autopsy. This clinical entity is routinely missed on transthoracic echocardiography. Injection drug use is a common predisposing factor, and Staphylococcus aureus is the most commonly identified organism. This report broadens the differential diagnosis of endovascular infections in injection drug users and highlights the importance of transesophageal echocardiography for diagnosis in selected patients.

Environmental investigations of Vibrio parahaemolyticus in oysters after outbreaks in Washington, Texas, and New York (1997 and 1998)

Total Vibrio parahaemolyticus densities and the occurrence of pathogenic strains in shellfish were determined following outbreaks in Washington, Texas, and New York. Recently developed nonradioactive DNA probes were utilized for the first time for direct enumeration of V. parahaemolyticus in environmental shellfish samples. V. parahaemolyticus was prevalent in oysters from Puget Sound, Wash.; Galveston Bay, Tex.; and Long Island Sound, N.Y., in the weeks following shellfish-associated outbreaks linked to these areas. However, only two samples (one each from Washington and Texas) were found to harbor total V. parahaemolyticus densities exceeding the level of concern of 10,000 g(-1). Pathogenic strains, defined as those hybridizing with tdh and/or trh probes, were detected in a few samples, mostly Puget Sound oysters, and at low densities (usually <10 g(-1)). Intensive sampling in Galveston Bay demonstrated relatively constant water temperature (27.8 to 31.7 degrees C) and V. parahaemolyticus levels (100 to 1,000 g(-1)) during the summer. Salinity varied from 14.9 to 29.3 ppt. A slight but significant (P < 0.05) negative correlation (-0.25) was observed between V. parahaemolyticus density and salinity. Based on our data, findings of more than 10,000 g(-1) total V. parahaemolyticus or >10 g(-1) tdh- and/or trh-positive V. parahaemolyticus in environmental oysters should be considered extraordinary.

Analysis of yeast MSH2-MSH6 suggests that the initiation of mismatch repair can be separated into discrete steps

The yeast MSH2-MSH6 complex is required to repair both base-pair and single base insertion/deletion mismatches. MSH2-MSH6 binds to mismatch substrates and displays an ATPase activity that is modulated by mispairs that are repaired in vivo. To understand early steps in mismatch repair, we analyzed mismatch repair (MMR) defective MSH2-msh6-F337A and MSH2-msh6-340 complexes that contained amino acid substitutions in the MSH6 mismatch recognition domain. While both heterodimers were defective in forming stable complexes with mismatch substrates, only MSH2-msh6-340 bound to homoduplex DNA with an affinity that was similar to that observed for MSH2-MSH6. Additional analyses suggested that stable binding to a mispair is not sufficient to initiate recruitment of downstream repair factors. Previously, we observed that MSH2-MSH6 forms a stable complex with a palindromic insertion mismatch that escapes correction by MMR in vivo. Here we show that this binding is not accompanied by either a modulation in MSH2-MSH6 ATPase activity or an ATP-dependent recruitment of the MLH1-PMS1 complex. Together, these observations suggest that early stages in MMR can be divided into distinct recognition, stable binding, and downstream factor recruitment steps.

Band-shaped and whorled microcystic dystrophy of the corneal epithelium

OBJECTIVE

To report the clinical, histopathologic, and electron microscopic features of band-shaped and whorled microcystic corneal epithelial dystrophy.

DESIGN

Two interventional case reports.

PARTICIPANTS

Two patients, two eyes.

INTERVENTION

The involved area of corneal epithelium was scraped from each cornea.

RESULTS

Histopathologic examination showed microscopic vacuoles in the epithelial cytoplasm in both cases. Electron microscopic examination revealed mainly empty cytoplasmic vacuoles with scant nonspecific osmophilic material. The process recurred clinically in one patient. Changes in corneal topography are documented in one patient.

CONCLUSION

Clinical findings and pathologic studies seem nearly identical to those in the original report. No pattern of systemic disorder or medication use was found. The cause of this condition remains unknown.

Gut focused behavioural treatment (biofeedback) for constipation and faecal incontinence in multiple sclerosis

OBJECTIVES

To determine whether gut focused behavioural treatment (biofeedback) is a useful therapy in multiple sclerosis patients referred for constipation, incontinence, or a combination of these symptoms. Most patients with multiple sclerosis complain of constipation, faecal incontinence, or a combination of the two. Patients rate these bowel symptoms as having a major impact on their life. Until now the management of these problems has been empirical, with a lack of evaluated therapeutic regimes.

METHODS

Thirteen patients (eight women, median age 38 years, median duration of multiple sclerosis 10 years) complaining of constipation, with or without faecal incontinence underwent a median of four sessions of behavioural treatment. Anorectal physiological tests were performed before therapy. Impairment and disability were rated with the Kurtzke score and the Cambridge multiple sclerosis basic score (CAMBS). Patients were contacted a median of 14 months after completion of treatment.

RESULTS

A beneficial effect was attributed to biofeedback in five patients. Mild to moderate disability, quiescent and non-relapsing disease, and absence of progression of multiple sclerosis over the year before biofeedback were predictive of symptom improvement. No physiological test predicted the response to therapy.

CONCLUSION

Biofeedback retraining is an effective treatment in some patients with multiple sclerosis complaining of constipation or faecal incontinence. A response is more likely in patients with limited disability and a non-progressive disease course.

Tensions used on girths on thoroughbred racehorses

OBJECTIVE

To determine commonly used girth tensions in Thoroughbred racehorses in the Melbourne metropolitan area.

DESIGN

A prospective industry survey.

METHODS

Strappers were instructed to tension girths, using the same saddle, under-saddle packing and girth, sufficiently to hold the saddle for racing. These tensions were continuously recorded by an in-line load cell in the girth. Seventeen strappers from five stables participated in the study, which was conducted on 91 horses.

RESULTS

Resting girth tensions varied considerably. The mean tension on inhalation was 13 +/- 0.4 kg. Male strappers recorded higher tensions than females for all indices measured. Age and girth size of the horse did not significantly influence results.

CONCLUSION

This study confirms that there is no standard for application of a girth and saddle in the Thoroughbred racing industry and the range of tensions applied was large. Strappers were unable to reliably apply the same tensions between horses. Values recorded at the extremes of the range seem inappropriate for racing conditions as low values would result in slippage of the saddle and higher values may result in girth galls and possible reduction in athletic performance. Further work is necessary to determine the point at which girth tension affects performance.

An outbreak of plague including cases with probable pneumonic infection, Ecuador, 1998

During February and March of 1998, 12 sudden deaths were reported among residents of a high-Andean community in Ecuador. All 12 fatalities were members of the same extended family and some had apparent exposure to sick guinea-pigs. Following an initial investigation by public health officials, an additional death was reported in a nearby community in April, also associated with exposure to sick guinea-pigs. Blood samples from humans, dogs, and a rodent were tested for antibody to the F1 antigen of Yersinia pestis by passive haemagglutination assay. Tissue from rodents was subjected to direct fluorescent antibody staining using fluorescein-labelled monoclonal antibody to Y. pestis F1 antigen. Formalin-fixed specimens from the 2 autopsies were evaluated using a 2-step alkaline phosphatase immunoassay with a monoclonal antibody to Y. pestis F1 antigen, and tissues that had not been embedded in paraffin were tested for the presence of DNA encoding the F1 structural antigen by polymerase chain reaction. Serological evaluation of close contacts of the fatalities revealed positive titres to F1 antigen of Y. pestis, the aetiological agent of plague, in 3 contacts from the first community and 1 from the second. Immunohistochemical staining of tissues collected from 2 of the fatalities provided evidence that both had pneumonic plague. Five of 14 dogs found in the communities were seropositive for plague antibody, providing evidence of a recent epizootic plague in the area.

Behavioural treatment (biofeedback) for constipation following hysterectomy

BACKGROUND

Constipation after hysterectomy has been postulated to be due to pelvic nerve damage, but there may be emotional or reversible physical factors of pathophysiological relevance. The aim of this study was to determine whether such constipation is responsive to behavioural treatment.

METHODS

Three groups of patients who had completed a course of biofeedback treatment were compared: women with no history of abdominal or pelvic surgery (n = 25), women for whom a hysterectomy had led to no change in bowel function (n = 27) and women who stated that their constipation was precipitated (n = 18) or severely worsened (n = 8) by hysterectomy. Pretreatment and post-treatment details about bowel function and symptoms were assessed using structured interview, and pretreatment whole-gut transit time and anorectal physiology testing were assessed for prognostic relevance.

RESULTS

Follow-up after completing treatment was a median of 28 (range 12-44) months. Forty-eight of 78 patients considered that their constipation had improved with treatment; the proportion in each group was similar (P = 0.73). Biofeedback reduced the need to strain, reduced abdominal pain, improved bowel frequency, and reduced laxative use to a similar degree in all three groups. Thirty-three of 53 patients with slow transit considered there was an improvement, compared with 15 of 22 with measured normal transit. Physiological testing did not predict outcome and did not differ between the three groups.

CONCLUSION

The majority of patients complaining of constipation induced or worsened by hysterectomy respond subjectively to behavioural treatment, in a similar proportion to those with idiopathic constipation. In contrast to the widely held view that nerve damage is responsible for symptoms, reversible factors are likely to be important in many patients.

Effects of an Intergenerational Choir for Community-Based Seniors and College Students on Age-Related Attitudes

The purpose of this study was to examine attitudes of college students and senior citizens towards each other by incorporating successful components of a senior citizens' music program into the "Adopt-A-Choir" program established in a university music education/therapy program. Data collection was accomplished using the Age Group Evaluation and Description Inventory (AGED), providing insight into attitudes classified in 4 domains/evaluative scales: Goodness, Positiveness, Vitality, and Maturity. Subjects ware members of the Senior Singers (n = 15, 15) and music education/therapy students enrolled in the Woman's Glee Club at a local university (n = 15, 12). Results of the pre/post AGED survey warn compared using the Wilcoxon Matched Pairs test, with means increasing significantly for the four domains (p <.02). Gains were greatest for the seniors, suggesting a stronger move from negative to positive attitudes. Though the gains were smaller with the university students, all changes were positive, with one exception: in the "vitality" domain, university student attitude ratings decreased on the continuum for "timid-assertive." Informal predictors further suggested the partnership between seniors and university students was enjoyed by both sets of participants.

Historical Genetics: The Parentage of Chardonnay, Gamay, and Other Wine Grapes of Northeastern France

The origins of the classic European wine grapes (Vitis vinifera) have been the subject of much speculation. In a search for parental relationships, microsatellite loci were analyzed in more than 300 grape cultivars. Sixteen wine grapes that have long been grown in northeastern France, including 'Chardonnay', 'Gamay noir', 'Aligoté', and 'Melon', have microsatellite genotypes consistent with their being the progeny of a single pair of parents, 'Pinot' and 'Gouais blanc', both of which were widespread in this region in the Middle Ages. Parentage analysis at 32 microsatellite loci provides statistical support for these relationships.

A mutation in the MSH6 subunit of the Saccharomyces cerevisiae MSH2-MSH6 complex disrupts mismatch recognition

In yeast, MSH2 interacts with MSH6 to repair base pair mismatches and single nucleotide insertion/deletion mismatches and with MSH3 to recognize small loop insertion/deletion mismatches. We identified a msh6 mutation (msh6-F337A) that when overexpressed in wild type strains conferred a defect in both MSH2-MSH6- and MSH2-MSH3-dependent mismatch repair pathways. Genetic analysis suggested that this phenotype was due to msh6-F337A sequestering MSH2 and preventing it from interacting with MSH3 and MSH6. In UV cross-linking, filter binding, and gel retardation assays, the MSH2-msh6-F337A complex displayed a mismatch recognition defect. These observations, in conjunction with ATPase and dissociation rate analysis, suggested that MSH2-msh6-F337A formed an unproductive complex that was unable to stably bind to mismatch DNA.

Neutron reflectivity studies of critical adsorption: the correspondence between a critical adsorption profile and specular neutron reflection

For interfacial order parameter profiles which decay as Az(-mu), such as the composition profile of the noncritical interface of a binary liquid mixture at a critical end point, there is a reported one-to-one correspondence between the profile and the reflectivity which can be described by an analytical theory [S. Dietrich and R. Schack, Phys. Rev. Lett. 58, 140 (1987)]. Evidence for mu=0.53+/-0.02 for adsorption at the hydrophilic silicon/liquid surface of the mixture (2-butoxyethanol+deuterium oxide) near its lower critical end point, determined from neutron reflectivity measurements, is presented. This value is in good agreement with the theoretical prediction of mu=0.516+/-0.004. Further examination of the data permits the determination of the asymptotic surface enrichment scaling factor amplitude P0 approximately 0.11, which is not in agreement with the theoretical value P(0) = 0.94+/-0.05 and values determined by other experimental methods.

Developing culturally sensitive HIV/AIDS and substance abuse prevention curricula for Native American youth

In 1990, researchers and health care professionals joined with members of several southwestern Native American communities to form an HIV/AIDS and substance abuse prevention partnership. Culturally sensitive approaches to theory-based interventions were developed into highly replicable, structured, school-based and community-based intervention programs. Process evaluations indicated high levels of program acceptance and fidelity. Outcome evaluations demonstrated significant positive preventive intervention effects among participants. This article reports how NAPPASA school prevention curricula were developed and discusses three critical processes in developing these successful curricula: 1) selection of integrative theory to address the multi-dimensional antecedents of HIV/AIDS and substance abuse among Native Americans, 2) use of ethnographic methodology to obtain intensive input from target groups and community members to ensure cultural and developmental sensitivity in the curriculum, and 3) use of process and outcome evaluations of pilot and field trials to develop an optimal curriculum.

The pharmacology of GR203040, a novel, potent and selective non-peptide tachykinin NK1 receptor antagonist

1. The in vitro and in vivo pharmacology of GR203040 ((2S, 3S)-2-methoxy-5-tetrazol-1-yl-benzyl-(2-phenyl-piperidin-3-y l)-amine), a novel, highly potent and selective non-peptide tachykinin NK1 receptor antagonist, was investigated in the present study. 2. GR203040 potently inhibited [3H]-substance P binding to human NK1 receptors expressed in Chinese hamster ovary (CHO) and U373 MG astrocytoma cells, and NK1 receptors in ferret and gerbil cortex (pKi values of 10.3, 10.5, 10.1 and 10.1 respectively). GR203040 had lower affinity at rat NK1 receptors (pKi = 8.6) and little affinity for human NK2 receptors (pKi < 5.0) in CHO cells and NK3 receptors in guinea-pig cortex (pKi < 6.0). With the exception of the histamine H1 receptor (pIC50 = 7.5). GR203040 had little affinity (pIC50 < 6.0) at all non-NK1 receptors and ion channels examined. Furthermore, GR203040 produced only weak inhibition of Na+ currents in SH-SY5Y neuroblastoma and superior cervical ganglion cells (pIC50 values < 4.0). GR203040 produced only weak antagonism of Ca(2+)-evoked contractions of rat isolated portal vein (pKn = 4.1). The enantiomer of GR203040, GR205608 (2R, 3R)-2-methoxy-5-tetrazol-1-yl-benzyl-(2-phenyl-piperidin-3-y l)-amine), had 10,000 fold lower affinity at the human NK1 receptor expressed in CHO cells (pKi = 6.3). 3. In gerbil ex vivo binding experiments, GR203040 produced a dose-dependent inhibition of the binding of [3H]-substance P to cerebral cortical membranes (ED50 = 15 micrograms kg-1 s.c. and 0.42 mg kg-1 p.o.). At 10 micrograms kg-1 s.c., the inhibition of [3H]-substance P binding was maintained for > 6 h. In the rat, GR203040 was less potent (ED50 = 15.4 mg kg-1 s.c.) probably reflecting, at least in part, its lower affinity at the rat NK1 receptor. 4. In guinea-pig isolated ileum and dog isolated middle cerebral and basilar arteries, GR203040 produced a rightward displacement of the concentration-effect curves to substance P methyl ester (SPOMe) with suppression of the maximum agonist response (apparent pKB values of 11.9, 11.2 and 11.1 respectively). 5. In anaesthetized rabbits, GR203040 antagonized reductions in carotid arterial vascular resistance evoked by SPOMe, injected via the lingual artery (DR10 (i.e. the dose producing a dose-ratio of 10) = 1.1 micrograms kg-1, i.v.). At a dose 20 fold greater than its DR10 value (i.e. 22 micrograms kg-1, i.v.), significant antagonism was evident more than 2 h after GR203040 administration. 6. In anaesthetized rats, GR203040 (3 and 10 mg kg-1, i.v.) produced a dose-dependent inhibition of plasma protein extravasation in dura mater, conjunctiva, eyelid and lip in response to electrical stimulation of the trigeminal ganglion. 7. It is concluded that GR203040 is one of the most potent and selective NK1 receptor antagonists yet described, and as such, has considerable potential as a pharmacological tool to characterize the physiological and pathological roles of substance P and NK1 receptors. GR203040 may also have potential as a novel therapeutic agent for the treatment of conditions such as migraine, emesis and pain.

Non-specific effects of the tachykinin NK1 receptor antagonist, CP-99,994, in antinociceptive tests in rat, mouse and gerbil

We have examined the antinociceptive activity of the potent and selective tachykinin NK1 receptor antagonist, CP-99,994, and its less active enantiomer, CP-100,263, in a variety of models in rat, mouse and gerbil. Administered systemically to gerbil or mouse CP-99,994 but not CP-100,263 stereo selectively inhibited a caudally directed biting and scratching elicited by intrathecal administration of the tachykinin NK1 receptor agonist, GR73632. In contrast, both CP-99,994 (ED50 = 3 (1-6) mumol.kg-1 s.c.) and CP-100,263 (4 (2-10)), were equipotent at inhibiting acetylcholine-induced abdominal constrictions in mice. Similarly, both enantiomers were also equipotent in reducing formalin-induced licking in gerbil (CP-99,994 (10.1 (5.7-18.6)), CP-100,263 (13.8 (7.8-27.1)) and rat (100 mumol.kg-1 s.c.). Finally, in the spinalised, anaesthetised rat, CP-99,994 dose-dependently and significantly inhibited the flexion reflex evoked by noxious pinch (5.0 (3.3-7.5) mumol.kg-1 i.v.), whereas the less active enantiomer, CP-100,263, was without significant effect when tested up to 30 mumol.kg-1. Our results demonstrate that in the spinal cord, CP-99,994 exhibits a tachykinin NK1 receptor mediated antinociceptive action.

The use of activated clotting times to monitor heparin therapy during and after interventional procedures

Use of the activated clotting time (ACT) was recommended in the mid 1970s to guide administration and reversal of heparin during cardiopulmonary bypass. As the applications of cardiopulmonary bypass spread, so too did the need for more efficient techniques to assess coagulation status. This led to the development of automated ACT measurements. Today, the importance of coagulation and anticoagulation has been further highlighted by recent advances in the field of interventional cardiology. More and more cardiologists are using in-laboratory bedside coagulation monitoring to assess heparin requirements during interventional procedures such as percutaneous transluminal coronary angioplasty (PTCA). This review focuses on the development of anticoagulation monitoring and provides historic information on the clinical use of heparin. The application of ACTs in the catheterization laboratory and in other clinical situations is discussed, along with alternative methods for bedside assessment of coagulation status. No definite guidelines have been established for ACT monitoring during invasive intravascular procedures; thus its role continues to be refined. In the meantime, the ACT appears to be an extremely useful method for monitoring heparin therapy and the adequacy of anticoagulation.

Risk assessment for aflatoxin: an evaluation based on the multistage model

Lifetime cancer potency of aflatoxin was assessed based on the Yeh et al. study from China in which both aflatoxin exposure and hepatitis B prevalence were measured. This study provides the best available information for estimating the carcinogenic risk posed by aflatoxin to the U.S. population. Cancer potency of aflatoxin was estimated using a biologically motivated risk assessment model. The best estimate of aflatoxin potency was 9 (mg/kg/day)-1 for individuals negative for hepatitis B and 230 (mg/kg/day)-1 for individuals positive for hepatitis B.

A double-blind, placebo-controlled trial of sustained-release diltiazem in patients with angina. Sustained-Release Diltiazem Study Group

The efficacy of a new sustained-release formulation of diltiazem was examined in a placebo-controlled, double-blind trial in patients with stable angina. Doses of 60 mg BID, 90 mg BID, 180 mg BID and 240 mg BID were compared with placebo in 208 patients at 3 hours and 12 hours after dosing. Diltiazem, in doses of 90 mg BID and 180 mg BID, was statistically superior to placebo with respect to increasing total exercise time. Treadmill exercise time at 3 hours postdose increased with placebo from 356.1 +/- 118.7 sec to 375.7 +/- 119.8 sec (NS); with 90 mg BID, 382.7 +/- 111.8 sec to 445.4 +/- 117.5 sec (P < 0.005); and with 180 mg BID, 386.8 +/- 145.9 sec to 467.2 +/- 166.2 sec (P < 0.0001). At 12 hours postdose, treadmill exercise time with placebo increased from 357.6 +/- 128.3 sec to 383.8 +/- 128.7 sec (NS); with 90 mg BID, 395.2 +/- 119.4 sec to 449.7 +/- 123.1 sec (P = 0.053); with 180 mg BID, 395.3 +/- 141.4 sec to 476.6 +/- 165.6 sec (P < 0.0001). Time to onset of angina was also increased by the 180-mg-BID dose both at 3 hours postdose (257.3 +/- 126.8 sec to 354.3 +/- 158.7 sec; P < 0.0001) and at 12 hours postdose (274.7 +/- 131.2 sec to 377.4 +/- 186.2 sec; P < 0.0001). Sustained-release diltiazem is effective and safe in treating patients with chronic stable angina.

Preoperative ultrasound and thallium-technetium subtraction scintigraphy in localizing parathyroid lesions in patients with hyperparathyroidism

Clinical and biochemical evaluation of patients with hypercalcemia are today extremely accurate in identifying those with primary hyperparathyroidism. Neck exploration by an experienced parathyroid surgeon is equally likely to identify correctly the diseased gland or glands. It has been suggested that recently devised localization techniques may allow the surgeon to limit the extent of the procedure to one side of the neck. The present retrospective study was undertaken to determine the reliability with which two such imaging procedures, ultrasonography (US) and thallium-technetium subtraction scanning (TTSS) localize these lesions by specific site or side. The identity of each patient undergoing parathyroidectomy at a metropolitan medical center was determined by review of the operating room log. From the records of each subject were noted the results of any imaging studies done, the location of lesions found at surgery, and the histologic diagnosis. Accuracy and positive predictive value of US and TTSS were then calculated on the basis of precise and lateralizing localization. Seventy-four patients underwent primary neck exploration during the study period. In 69 patients US, TTSS, or both were performed preoperatively, and among these, data were complete in 65. Ultrasound correctly localized the site of a lesion in 31 of 63 subjects, and TTSS in 25 of 45. Ultrasound correctly localized the side on which the lesion lay in 35 of 62 subjects, and TTSS in 27 of 45. In 29 of 42, one or both studies correctly identified the side on which the lesion lay. In only one of 13 subjects with hyperplasia were all four glands correctly identified as hyperplastic.(ABSTRACT TRUNCATED AT 250 WORDS)