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Biomedical subjects

C M Smith

Publications and source records attributed to C M Smith.

At least 55 records · Page 3Linked to original sources
PubMed1999

The catalytic subunit of cAMP-dependent protein kinase: prototype for an extended network of communication.

The protein kinase catalytic core in essence comprises an extended network of interactions that link distal parts of the molecule to the active site where they facilitate phosphoryl transfer from ATP to protein substrate. This review defines key sequence and structural elements, describes what is currently known about the molecular interactions, and how they are involved in catalysis.

Amino Acid Sequence↗
PubMed1999

Discrimination of refractory periodontitis subjects using clinical and laboratory parameters alone and in combination.

The purpose of the present investigation was to use baseline clinical and laboratory parameters to distinguish subjects refractory to conventional periodontal therapy. Baseline clinical, microbial and host parameters were compared in 61 successfully-treated and 27 refractory subjects. Refractory subjects showed mean full-mouth attachment level (AL) loss and/or >3 sites with new AL loss >2.5 mm within 1 year after both scaling and root planing and surgery with systemic tetracycline. Successfully-treated subjects showed mean AL gain and no sites with new AL loss >2.5 mm after either regimen. Gingival redness, bleeding on probing, suppuration, supragingival plaque accumulation, pocket depth and AL were measured at 6 sites per tooth in each subject. The levels of 40 subgingival taxa were determined in subgingival plaque samples from up to 28 sites in each subject using checkerboard DNA-DNA hybridization. Serum antibody (Ab) to 85 subgingival species was determined using checkerboard immunoblotting. Levels of serum IgG2 and Gm23 allotype were measured using radial immunodiffusion; FcgammaRIIa and FcgammaRIIIb receptor haplotypes were determined using PCR and allele specific oligonucleotide probes. Odds ratios of a subject being refractory were determined by comparing measured parameters in the 2 subject groups using univariate and multivariate techniques. 17 of 151 clinical, microbial and immunological variables were significant using chi2 analysis after adjusting for multiple comparisons. For example, the odds ratios of a subject being refractory were 12.2, 5.4 and 6.9 if the subject had Ab >50 microg/ml to >9 species; S. constellatus counts >2.4% of the total DNA probe count or >2.1% of sites with AL >6 mm. The 17 significant predictor variables were used in logistic regression and discriminant analyses. Similar variables were selected using both analyses including the number of serum Ab to subgingival species >50 microg/ml, % S. constellatus in plaque samples and % sites with attachment loss >6 mm. In the logistic regression analysis model, the odds ratios associated with >9 species exhibiting >Ab 50 microg/ml, >2.1% of sites with AL >6 mm and >2.4% S. constellatus in plaque were 8.7, 6.8 and 2.4, respectively, after adjusting for other variables in the model. Discriminant analysis using these variables provided sensitivity, specificity, positive and negative predictive values of 0.66, 0.92, 0.80 and 0.85 respectively. Refractory periodontitis subjects could be distinguished using a subset of clinical, microbiological and immunological parameters.

Adult↗
PubMed1999

Inherited prion disease with an alanine to valine mutation at codon 117 in the prion protein gene.

A large English family with autosomal dominant segregation of presenile dementia, ataxia and other neuropsychiatric features is described. Diagnoses of demyelinating disease, Alzheimer's disease, Creutzfeldt-Jakob disease (CJD) and Gerstmann-Sträussler-Scheinker syndrome have been attributed to particular individuals at different times. An Irish family, likely to be part of the same kindred, is also described, in which diagnoses of multiple sclerosis, dementia, corticobasal degeneration and new variant CJD have been considered in affected individuals. Molecular genetic studies have enabled the classification of this disease at the molecular level as one of the group of inherited prion diseases, with the substitution of valine for alanine at codon 117 of the prion protein gene (PRNP). Only three other kindreds have been described world-wide with this mutation and only limited phenotypic information has been reported. Here we describe the phenotypic spectrum of inherited prion disease (PrPA117V). The diversity of phenotypic expression seen in this kindred emphasizes the logic of molecular classification of the inherited prion diseases rather than classification by specific clinicopathological syndrome. Indeed, inherited prion disease should be excluded by PRNP analysis in any individual presenting with atypical presenile dementia or neuropsychiatric features and ataxia, including suspected cases of new variant CJD.

Adult↗
PubMed1999

Late-form hemorrhagic disease of the newborn: a fatal case report with illustration of investigations that may assist in avoiding the mistaken diagnosis of child abuse.

Hemorrhagic disease of the newborn (HDN) is usually a self-limiting hemorrhagic disorder of childhood that occurs as a result of vitamin K deficiency. It may be defined as early or late form depending on the time of onset related to birth. HDN is recognized as one of several bleeding disorders that can mimic the findings of nonaccidental head injury and may lead to a mistaken diagnosis of child abuse. We present a single fatal case of late-onset HDN with illustration of hematologic assays that can be performed to assist the pathologist in making the correct diagnosis of HDN.

Biomarkers↗
PubMed1999

RNase H requirements for the second strand transfer reaction of human immunodeficiency virus type 1 reverse transcription.

Retroviral reverse transcriptase (RT) enzymes are responsible for transcribing viral RNA into double-stranded DNA. An in vitro assay to analyze the second strand transfer event during human immunodeficiency virus type 1 (HIV-1) reverse transcription has been developed. Model substrates were constructed which mimic the viral intermediate found during plus-strand strong-stop synthesis. Utilizing wild-type HIV-1 RT and a mutant E478Q RT, the requirement for RNase H activity in this strand transfer event was analyzed. In the presence of Mg2+, HIV-1 RT was able to fully support the second strand transfer reaction in vitro. However, in the presence of Mg2+, the E478Q RT mutant had no detectable RNase H activity and was unable to support strand transfer. In the presence of Mn2+, the E478Q RT yields the initial endoribonucleolytic cleavage at the penultimate C residue of the tRNA primer yet does not support strand transfer. This suggests that subsequent degradation of the RNA primer by the RNase H domain was required for strand transfer. In reactions in which the E478Q RT was complemented with exogenous RNase H enzymes, strand transfer was supported. Additionally, we have shown that HIV-1 RT is capable of supporting strand transfer with substrates that mimic tRNAHis as well as the authentic tRNA3Lys.

Base Sequence↗
PubMed1999

Obligatory cessation of smoking by psychiatric inpatients.

OBJECTIVE: Signs and symptoms of nicotine withdrawal and alterations in psychopathology were evaluated among acutely ill psychiatric patients admitted to a hospital with a smoking ban. It was hypothesized that smokers would experience symptoms of withdrawal and that these symptoms would aggravate and confound psychiatric symptoms. METHODS: Sixty acute psychiatric inpatients, 44 of whom were smokers, were assessed on three consecutive days using the Nicotine Withdrawal Checklist (NWC) and the Brief Psychiatric Rating Scale (BPRS). RESULTS: BPRS scores were significantly and positively correlated from day 1 through day 3, as were NWC scores. Mean BPRS scores declined significantly from day 1 to day 3, and mean NWC scores declined significantly from day 1 to day 2. Although smokers reported increased tension over the three days and a greater persistence of anxiety compared with nonsmokers, no statistically significant differences in overall BPRS scores were found between the two groups. In contrast, symptoms of nicotine withdrawal occurred significantly more frequently among smokers and were statistically significantly correlated with scores on the Fagerstrom Tolerance Questionnaire, which assesses the degree of nicotine dependence. Despite subjects' reports of feeling distressed and of experiencing nicotine withdrawal symptoms, abrupt cessation of smoking did not significantly affect either the severity or the improvement of psychopathological symptoms during hospitalization. No specific diagnostic group appeared to be selectively sensitive to nicotine withdrawal symptoms. CONCLUSIONS: No immediate benefits or adverse effects from the smoking ban were detected. No compelling reasons to reverse the smoking ban were observed.

Adult↗
PubMed1999

A clozapine overdose with markedly elevated serum levels.

Clozapine (Clozaril) is an atypical antipsychotic agent used to treat schizophrenia refractory to other pharmacological agents. This report describes an accidental clozapine overdose. The half-life of clozapine in this patient was determined from two blood levels, one obtained on admission and the second 10.5 hours later. The calculated half-life of 8.11 hours is consistent with published levels for single doses and suggests an apparent stability in clozapine elimination half-life in the face of overdose. The maximum clozapine blood level attained was probably among the highest nonfatal levels reported. The patient recovered fully following hospital admission for monitoring and supportive care. This case report illustrates the usefulness of following the time course of the changes in blood level at selected time intervals, as well as the importance of entertaining a diagnosis of drug overdose in patients presenting with acute mental status changes.

Adult↗
PubMed1999

The bronchoprotective effect of inhaled salmeterol in preschool children: a dose-ranging study.

The optimal dose of salmeterol in infants and preschool children is not known. The aim of this study was to assess the bronchoprotective effect of different doses of salmeterol using methacholine-induced wheeze in children aged <4 yrs. Children <4 yrs old with a history of recurrent wheeze underwent two methacholine challenges within 7 days. One hour before each challenge they were pretreated in double-blind fashion using a metered-dose inhaler and Babyhaler spacer. Placebo was given before one challenge, and either 25, 50 or 100 microg of salmeterol before the other. Both the dose and treatment order were random. The provocative concentration of methacholine causing wheeze (PCwheeze) was measured on each occasion. Studies were terminated when wheeze occurred or arterial oxygen saturation (Sa,o2) fell below 91%. Of the 42 children enrolled, 33 completed the study. Two subjects refused the challenge test, two failed to return and five developed upper respiratory tract infections or wheeze between the two tests. The mean (range) age of the population was 27 (8-46) months. Ratios of PCwheeze between treatment and placebo challenges were calculated for each dosage group. The treatment/placebo ratios (95% confidence intervals) were 1.2 (0.6-2.4) for 25 microg, 2.5 (1.4-4.6) for 50 microg (p<0.01), and 4.0 (2.1-7.4) (p<0.001) for 100 microg doses. In recurrently wheezy children aged <4 yrs a single dose of salmeterol between 25 and 100 microg has a dose-dependent effect on methacholine-induced wheeze, and this is significantly different from placebo at 50 and 100 microg. This study suggests that the Babyhaler effectively delivers salmeterol to children <4 yrs of age and that doses between 50-100 microg are efficacious.

Administration, Inhalation↗
PubMed1999

Methacholine challenge in preschool children: methacholine-induced wheeze versus transcutaneous oximetry.

Tracheal/chest auscultation for wheeze and transcutaneous oximetry have both been suggested as measures of outcome in bronchial provocation tests in young children. This study aimed to compare the sensitivity and safety of these two techniques as end-points for methacholine challenge in children aged <4 yrs. Seventy-two methacholine challenges were performed in 39 children aged <4 yrs with recurrent wheeze. Arterial oxygen saturation (Sa,O2) and transcutaneous oxygen pressure tcPO2 continuously, and the test was terminated when wheeze was heard or at Sa,O2 <91%. tcPO2 was not used as an end-point. Wheeze or desaturation occurred at < or =8 mg x mL(-1) methacholine in every test. One child had transient clinical cyanosis, but no other ill-effects were seen. Fifty-six tests (78%) were terminated for wheeze, seven (10%) for fall in Sa,O2 and nine (12%) showed simultaneous responses in both parameters. Twenty-eight tests (39%) contained a fall in tcPO2 >3 kPa but six of these also showed a significant rise. Fifty-three tests (75%) contained a fall in tcPO2 >15%, but 20 of these also showed a significant rise. Tracheal/chest auscultation with Sa,O2 monitoring is a sensitive and relatively safe end-point for bronchial challenges in preschool children. The erratic pattern of transcutaneous oxygen pressure response in some children casts doubt on its reliability as a proxy measure of bronchial obstruction.

Auscultation↗
PubMed1999

Attitudes towards alcoholics anonymous by dually diagnosed psychiatric inpatients.

Self-help programs such as Alcoholics Anonymous (AA) have been viewed as beneficial adjuncts to comprehensive treatment programs for the treatment of alcohol use disorders. The usefulness of such programs for individuals with dual psychiatric disorders has not been established. This study examined the alcohol and psychiatric treatment histories of 60 psychiatric inpatients with concomitant alcohol use or abuse with attention to the frequency and correlates with past AA attendance. Most subjects reported feeling comfortable with the basic tenets of AA; neither diagnosis nor gender was related to AA participation, belief in its basic tenets, or willingness to attend AA in the future. Regular, past attendance at AA was surprisingly high (37%) and was not different for individuals with schizophrenic spectrum disorders compared to those with other psychiatric disorders. The majority reported plans to attend AA as part of their outpatient treatment program. The potential benefits of AA for dual diagnosis individuals deserve further attention.

Adult↗
PubMed1999

Primary intracerebral lymphoma: A clinicopathological study of 28 patients.

Primary intracerebral lymphoma is an uncommon presenting site for non-Hodgkin's lymphoma. The authors review 28 histopathologically confirmed, consecutive cases, presenting over a 15-year period. The cohort included 20 males and 8 females with a mean age at diagnosis of 54 years (range 27-75 years). Subtotal resection was performed in 8 patients. Radical whole brain irradiation was given to 27 patients. One patient was too unwell to receive treatment and quickly died. Three patients also had chemotherapy. Clinical remission was achieved in 19 patients. Of these, 9 relapsed after a median interval of 18 months. Nine patients (32% total cohort) are still alive and in remission after a median follow-up of 2 years and 10 months (range 11 months to 11 years and 5 months). Cause of death was intracerebral lymphoma in 13 of the 19 patients who died. Median survival was 12 months in this group (range 1 week to 4 years and 9 months). Actuarial 5-year survival for all patients was 19%. The prognosis for patients with primary intracerebral lymphoma treated with radiotherapy alone is poor.

Adult↗
PubMed1999

Liver transplantation in the United States: a report from the UNOS Liver Transplant Registry.

Transplants and centers Between 1988 and 1998 the number of liver transplants performed in the US more than doubled from 1,713 to 4,487; the number of centers increased from 59 to 116. The number of living donor, segmental, and multiple organ transplants also increased over time. The rate of increase in the number of centers has slowed over the last few years. Outcomes. Survival among pediatric recipients. The one- and 7-year graft survival rates for pediatric recipients were 72% and 62%, respectively. The one- and 7-year patient survival rates were 85% and 79%. Patient survival did not decrease much after the first 2 years and graft survival stabilized after 4 years posttransplant. Some of the factors associated with increased odds of graft failure and patient death at 6 months posttransplant included having a previous transplant; being hospitalized, in the ICU, or on life support at the time of transplant; creatinine > 2 mg/dl; donor age and race/ethnicity; and transplant type. Factors associated with decreased odds of graft failure or patient death were recipient gender, recipient race/ethnicity, having a metabolic disease and receiving a living donor liver. Among grafts/recipients surviving the first 6 months after transplantation, recipient race/ethnicity, primary liver disease, having a previous transplant, donor age and race/ethnicity, and transplant type were associated with a greater relative risk of graft failure and mortality. Survival among adult recipients. The one- and 7-year graft survival rates among adult recipients were 77% and 57%, respectively. The one- and 7-year patient survival rates were 85% and 67%. Survival rates decreased steadily at all time points following transplantation. Some of the factors associated with increased odds of graft failure and mortality at 6 months after transplantation were recipient age and race/ethnicity; primary liver disease; having a previous transplant; being hospitalized, in the ICU, or on life support at the time of transplant; longer cold ischemia time; older donor age, race/ethnicity, or gender; and having a non-identical recipient/donor blood type match. Having cholestatic liver disease/cirrhosis and shorter cold ischemia times were associated with decreased odds of graft failure and mortality. Many of these characteristics also affected grafts and patients surviving the first 6 months, including recipient race/ethnicity, primary liver disease, previous transplant, and donor age.

Adolescent↗
PubMed1998

Clinical, radiological, neurophysiological, and neuropathological characteristics of gluten ataxia.

BACKGROUND: Ataxia is the commonest neurological manifestation of coeliac disease. Some individuals with genetic susceptibility to the disease have serological evidence of gluten sensitivity without overt gastrointestinal symptoms or evidence of small-bowel inflammation. The sole manifestation of disease in such patients may be ataxia. We describe the clinical, radiological, and neurophysiological features of this disorder. METHODS: Patients with ataxia attending the neurology outpatient clinics at the Royal Hallamshire Hospital, Sheffield, UK, were screened for gluten sensitivity as shown by the titre of antibody to gliadin. Those with other causes of ataxia were excluded. We carried out clinical, neurophysiological, neuroradiological, and, in two cases, neuropathological examinations. FINDINGS: 28 patients with gluten ataxia were identified. All had gait ataxia and most had limb ataxia. Those with more severe gait ataxia had longer disease duration. No patient had tremor or other extrapyramidal features. 19 patients showed some form of peripheral neuropathy on neurophysiological examination. 16 patients had no gastrointestinal symptoms. Distal duodenal biopsy showed lymphocytic infiltration in two patients, and changes compatible with coeliac disease in 11. Six patients had evidence of cerebellar atrophy on magnetic-resonance imaging. Necropsy was done on two patients who died; there was lymphocytic infiltration of the cerebellum, damage to the posterior columns of the spinal cord, and sparse infiltration of the peripheral nerves. INTERPRETATION: Gluten sensitivity is an important cause of apparently idiopathic ataxia and may be progressive. The ataxia is a result of immunological damage to the cerebellum, to the posterior columns of the spinal cord, and to peripheral nerves. We propose the term gluten ataxia to describe this disorder.

Adult↗
PubMed1998

New 1alpha,25-dihydroxy-19-norvitamin D3 compounds of high biological activity: synthesis and biological evaluation of 2-hydroxymethyl, 2-methyl, and 2-methylene analogues.

New highly active isomers of the natural hormone 1alpha, 25-dihydroxyvitamin D3 possessing an exomethylene group at the 2-position were prepared in a convergent manner, starting with (-)-quinic acid and the corresponding (20R)- and (20S)-25-hydroxy Grundmann ketones. These 2-methylene-19-norvitamins were efficiently converted to the 2-methyl and 2-hydroxymethyl derivatives, some of which exhibited pronounced in vivo biological activity. Configurations of the A-ring substituents were determined by 1H NOE difference spectroscopy as well as by spin decoupling experiments. It was established that the bulky methyl and hydroxymethyl substituents at C-2, due to their large conformational free energies, occupy mainly equatorial positions. Additionally, hydroxylation of the C(10)-C(19) double bond in 1alpha,25-(OH)2D3 was performed, resulting in 1alpha,19,25-trihydroxy-10,19-dihydrovitamin D3 derivatives in which the hydroxymethyl substituent at C-10, for steric reasons, is forced to occupy an axial position. In consequence, the vitamin D3 analogues were synthesized in which the 1alpha-hydroxy group, required for biological activity, is almost exclusively axially or equatorially oriented because of stabilization of the single A-ring chair conformations. The relative ability of the synthesized analogues to bind the porcine intestinal vitamin D receptor was assessed and compared with that of the natural hormone. It was established that vitamins possessing the axial orientation of the 1alpha-hydroxy substituent exhibit a significantly increased receptor binding affinity. Compounds with a 2-methylene substituent showed selective calcemic activity profiles, being extremely effective on bone calcium mobilization. 2alpha-Methyl-substituted vitamins proved to be much more active in vivo than the corresponding epimers with 2beta-configuration. All of the 2-substituted vitamins exhibited pronounced HL-60 differentiating activity, those 2alpha-substituted in the 20S-series being especially potent. The present studies imply that the axial orientation of the 1alpha-hydroxy group is necessary for biological activity of vitamin D compounds.

Animals↗
PubMed1998

Center-specific graft and patient survival rates: 1997 United Network for Organ Sharing (UNOS) report.

CONTEXT: Multiple comprehensive, risk-adjusted studies evaluating short-term surgical mortality have been reported previously. This report analyzes short-term and long-term outcomes, both nationally and at each individual transplant program, for all solid organ transplantations performed in the United States. OBJECTIVES: To report graft and patient survival rates for all solid organ transplantations, both nationally and at each specific transplant program in the United States, and to compare the expected survival rate with the actual survival rate of each individual program. DESIGN AND SETTING: Multivariate regression analysis of donor and recipient factors affecting graft and patient survival of all kidney, liver, pancreas, heart, lung, and heart-lung transplants reported to the United Network for Organ Sharing from 742 separate transplant programs. PATIENTS: A cohort of 97587 solid organ transplantations performed on 92966 recipients in the United States from January 1988 through April 1994. MAIN OUTCOME MEASURES: Short-term and conditional 3-year national and individual transplant program graft and patient survival rates overall and from 2 separate eras (era 1, January 1988-April 1992; era 2, May 1992-April 1994); comparison of actual center-specific performance with risk-adjusted expected performance and identification of centers with better-than-expected or worse-than-expected survival rates. RESULTS: One-year graft follow-up exceeded 98% and conditional 3-year follow-up exceeded 91% for all organs. Graft and patient survival improved significantly in era 2 compared with era 1 for all cadaver organs except heart, which remained the same. One-year cadaveric graft survival ranged from 81.5% for heart to 61.9% for heart-lung and 3-year conditional graft survival ranged from 91.3% for pancreas to 74.7% for lung. The percentage of programs whose actual 1-year graft survival was not different from or was better than their risk-adjusted expected survival ranged from 98.3% for heart-lung to 75.7% for liver. Most kidney, liver, and heart programs whose actual survival was significantly less than expected performed small numbers (less than the national average) of transplantations per year. CONCLUSIONS: Graft and patient survival for solid organ transplantations showed improvement over time. Conditional 3-year graft and patient survival rates were approximately 90% for all organs except for lung and heart-lung. The conditional 3-year survival rates were better than 1-year survival rates, indicating the major risk after transplantation occurs in the first year. The majority of transplant programs achieved actual survival rates not significantly different from their expected survival rates. Center effects were most significant within the first year after transplantation and had much less influence on long-term survival outcomes.

Actuarial Analysis↗
PubMed1998

Cell cycle length of olfactory bulb neuronal progenitors in the rostral migratory stream.

The anterior portion of the neonatal telencephalic subventricular zone (SVZa) contains proliferating cells that generate an immense number of neurons destined to become the granule and periglomerular cells of the olfactory bulb. In contrast to other immature neurons in the central nervous system, cells arising in the SVZa maintain the ability to divide as they traverse the rostral migratory stream to their final destinations despite expressing an antigenic marker of differentiated neurons (Menezes et al. [1995] Molec. Cell. Neurosci. 6:496-508). Because of their considerable proliferative capacities and unusual mitotic behavior, we decided to determine the cell cycle length of proliferating cells within the SVZa and within the migratory pathway used by SVZa-derived cells. Following the methodology of Nowakowski et al. [1989](J. Neurocytol. 18:311-318), postnatal day 2 rat pups were exposed to 5'-bromo-2'deoxyuridine (BrdU) for increasing periods of time before perfusion. By plotting the percentage of nuclei undergoing DNA synthesis in the SVZa at each time versus the BrdU labeling interval, we determined that approximately 15% of the SVZa population is actively dividing and that these cells have a cycle length of approximately 14 hr, significantly less than the 18.6 hr determined to be the cycle length of dividing cells in more posterior, glia-generating regions of the subventricular zone (Thomaidou et al. [1997] J. Neurosci. 17:1075-1085). The cycle length of cells dividing in the mid portion of the rostral migratory stream, however, is considerably longer: 17.3 hr. This may reflect the need for these cells to coordinate the processes of migration and division. Our studies also suggest that there may be regional differences in the types of descendants produced by the proliferating cells. Retroviral lineage tracing studies showed that those cells that divide within the rostral migratory stream, like proliferating cells within the SVZa, make cells destined for the olfactory bulb. Unlike the progenitors that divide within the SVZa and generate more granule cells than periglomerular cells, the proliferating cells within the migratory pathway generate more periglomerular cells than granule cells. Collectively the proliferating cells of the SVZa and migratory pathway produce a large number of olfactory bulb interneurons. Our work suggests that this may be achieved in part by the relatively rapid divisions of progenitor cells within the SVZa and in part by the ongoing division of migrating cells en route to the olfactory bulb.

Animals↗