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Biomedical subjects

D Wallace

Publications and source records attributed to D Wallace.

At least 55 records · Page 3Linked to original sources
PubMed2000

Abstinent-contingent housing and treatment retention among crack-cocaine-dependent homeless persons.

This study investigated Behavioral Day Treatment attendance in relation to treatment outcome among homeless persons dependent on crack-cocaine. Participants (N = 141) were 72.3% male and 82.7% African American. Days attended, activities attended, and follow-up rates over a 12-month period were positively affected by the more attractive treatment of providing immediate, rent-free, abstinent-contingent housing during a 2-month Behavioral Day Treatment program. Results replicated previous findings that abstinence is a function of treatment attendance and more treatment is associated with greater abstinence. The loss of predictive power at long-term follow-up, limitations of a retrospective design, need to identify most predictive therapeutic activity types, and potential influence of mental disorders were discussed. Analytical techniques used in this study allows for the planning, predictability, and measurement of drug abuse treatment success as a function of service utilization.

Adult↗
PubMed2000

Detection and prevalence of early diabetic retinopathy in juvenile diabetics with diabetes for 10 years or more.

PURPOSE: To compare clinical examination using green light with clinical examination using white light in detecting early diabetic retinopathy (DR) in juvenile diabetic patients with disease for 10 or more years. METHODS: All patients were examined clinically using both green light and white light to determine the presence of DR. Each patient underwent seven-field fundus photography, which was used as the defined standard against which the clinical examinations were compared and also to determine the prevalence of DR. Data on age at diagnosis, duration of diabetes mellitus, recent HbA1c levels, treatment for systemic hypertension and microalbuminuria were obtained from medical records. RESULTS: When compared with the defined standard, fundal examination with green light was more sensitive, more specific and had higher predictive values than examination with white light in the detection of early DR. The overall prevalence of DR was 44%, which in all cases was classified as minimal to mild background DR. Patients with DR had significantly higher mean HbA1c levels than those without (p = 0.016). There was no significant association between the prevalence of DR and age at time of examination or diagnosis, duration of diabetes, patient gender, microalbuminuria levels or treatment for systemic hypertension. CONCLUSION: Fundal examination with green light is better than white light in detecting early DR in juvenile diabetics with duration of disease of 10 years or more. Furthermore the presence of DR is associated with poorer diabetic control. Due to coincident lifestyle changes and the probability of long duration of disease, accurate detection of early DR in juvenile diabetics with diabetes for over 10 years is important.

Adolescent↗
PubMed2000

Uncommon mutations and polymorphisms in the hemochromatosis gene.

Hereditary hemochromatosis (HH) is a common autosomal recessive disorder of iron metabolism. Iron absorption from the gut is inappropriately high, resulting in increasing iron overload. The hemochromatosis gene (HFE) was identified in 1996 by extensive positional cloning by many groups over a period of about 20 years. Two missense mutations were identified. Homozygosity for one of these, a substitution of a tyrosine for a conserved cysteine (C282Y), has now clearly been shown to be associated with HH in 60-100% of patients. The role of the second mutation, the substitution of an aspartic acid for a histidine (H63D), is not so clear but compound heterozygotes for both these mutations have a significant risk of developing HH. Here we review other putative mutations in the HFE gene and document a number of diallelic polymorphisms in HFE introns.

Amino Acid Substitution↗
PubMed2000

Reliability of lower extremity isokinetic strength testing in adults with stroke.

OBJECTIVE: To evaluate the reliability of isokinetic strength testing of knee flexion and extension at 60 degrees per second, and ankle plantar flexion and dorsiflexion at 30 degrees per second in adults with stroke. DESIGN: Test-retest using intraclass correlation coefficients (ICC). SETTING: Human performance laboratory. SUBJECTS: Ten adults post stroke with a mean age of 64 years (five males) and 10 adults without neurological injury with a mean age of 69 years (three males) who served as controls. MAIN OUTCOME MEASURES: Peak torque and average torque. RESULTS: The reliability of strength of the less-affected lower extremity was high with values ranging from 0.75 to 0.97. Knee extension, ankle plantar flexion and the peak torque of dorsiflexion were reliable for the affected limb, ranging from 0.80 to 0.90. In contrast, affected knee flexion was not reliable with values of 0.48 and 0.44 for peak torque and average peak torque respectively. CONCLUSIONS: Isokinetic knee and ankle strength of the less-affected limb are reliable. Isokinetic strength of the affected lower extremity is also reliable with the noted exception of knee flexion.

Aged↗
PubMed2000

Mortality in male alcoholics after ten to fourteen years.

OBJECTIVE: Alcoholics frequently die prematurely. The purpose of this study was to determine: (1) whether subjects in a sample of 360 male alcoholics, followed over a period of 10-14 years, died prematurely: (2) if so, from what causes; and (3) whether such deaths are predictable from characteristics present at initial assessment. METHOD: Subjects were male veterans (N = 360) with a diagnosis of alcoholism admitted to an inpatient substance abuse treatment program at the Kansas City Veterans Affairs (VA) Medical Center during 1980-1984 who consented to participate in intake evaluations and subsequent follow-ups at 1 year and 10-14 years later. Of the 357 (99.2%) men located at the 10-14 year follow-up, 96 (26.6%) were confirmed as deceased, 255 survivors agreed to be reassessed and 6 subjects refused reassessment. Information regarding cause of death was obtained from death certificates, VA records and other sources. RESULTS: At intake, the subsequently deceased men were older, had less education, lower psychosocial functioning, more medical problems and greater psychiatric severity. Their overall death rate was 2.5 times greater than that of a reference group of men. Men in the 35-44 year age group were 5.5 times as likely to die. A statistical model utilizing measures of alcohol dependence to predict mortality from intake to 10-14 year follow-up indicated that alcoholics who limited drinking were half as likely to die whereas those who engaged in morning drinking were 2.5 times more likely to die. CONCLUSIONS: Alcoholic men, especially those in the group aged 35 to 44 years, have a significantly higher risk of premature death than a reference group of men. Men who engaged in morning drinking and could not limit drinking appeared to be at higher risk of mortality 10 years later.

Adult↗
PubMed2000

Surgical wound morbidity in an austere surgical environment.

Surgical wound morbidity was analyzed for a U.S. military field hospital deployed to the Republic of Haiti in support of Operation New Horizons 1998. The purpose of the analysis was to determine if procedures performed in the field hospital had greater infectious risks as a result of the environment compared with historical reports for traditional hospital or clinic settings. Acceptable historical infection rates of 1.5% for clean surgical cases, 7.7% for clean contaminated cases, 15.2% for contaminated cases, and 40% for dirty cases have been noted. There were 827 operations performed during a 6-month period, with the majority of patients assigned American Society of Anesthesiologists Physical Status Classification class I or II. The distribution of these cases was: 72% clean cases, 5% clean contaminated cases, 4% contaminated cases, and 19% dirty cases. The overall wound complication rate was 3.6%, which included 5 wound infections, 11 wound hematomas, 8 superficial wound separations, and 6 seromas. The infectious morbidity for clean cases, the index for evaluation of infectious complications, was 0.8%, well within the accepted standards. There were two major complications that required a return to the operating room: a wound dehiscence with infection in an orchiectomy, and a postoperative hematoma with airway compromise in a subtotal thyroidectomy. There were no surgical mortalities. The infectious wound morbidity for operations performed in the field hospital environment was found to be equivalent to that described for the fixed hospital or clinic settings. No special precautions were necessary to ensure a low infection rate. The safety for patients undergoing elective surgical procedures has been established. Further training using these types of facilities should not be limited based on concerns for surgical wound morbidity.

Adolescent↗
PubMed2000

The Breast Health Center at Women & Infants Hospital: origin, philosophy, and features.

The Breast Health Center, a component of the program in Women's Oncology at Women & Infants Hospital, is a multidisciplinary center devoted to the treatment and study of benign and malignant breast diseases. The philosophy, structure, and function of The Breast Health Center are described along with its specific components. The Breast Health Center's three fundamental missions of patient care, education, and research are discussed.

Biopsy↗
PubMed1999

Interpreting age, period and cohort effects in plasma lipids and serum insulin using repeated measures regression analysis: the CARDIA Study.

Observed changes in health-related behaviours and disease risk factors may arise from physiological or environmental changes, or from biases due to sampling or measurement errors. We illustrate problems in the interpretation of such changes with longitudinal data from the Coronary Artery Risk Development in Young Adults (CARDIA) study. Mean plasma cholesterol was 14 mg/dl higher in 27- than in 20-year-old black men cross-sectionally, but longitudinally it declined by 4 mg/dl during the 7 years. To sort out these contradictory assessments of the effect of age/passage of time, we estimated age and period effects under the assumptions that age effects are a smooth function of age independent of period, and that period effects are changes common to persons across all ages. Simple estimates the age effect, such as the cross-sectional age slopes, may be confounded by cohort effects, by interactions of time and age after baseline, or by the occurrence of non-linearities in response after baseline. We note examples of each potential type of bias. The data and background literature support the assumption that cohort effects do not seriously compromise interpretation for these variables in the CARDIA study. Strong secular decreases in plasma cholesterol, apparently due to population-wide dietary change, mask increases with ageing. Age increases in triglycerides are largely explained by increases in body fatness. For these data, we cautiously accept the cross-sectional age slope as an estimate of ageing and the age-matched time trend as an estimate of secular trend.

Adolescent↗
PubMed1999

Sympathetic-parasympathetic interactions at the heart in the anaesthetised rat.

This study observed the effects of stimulation of the cardiac sympathetic nerve on vagal slowing of the heart in rats, and compared these with any actions of exogenous neuropeptide Y (NPY) and galanin (GAL). In rats anaesthetised with pentobarbitone, stimulation of the cardiac sympathetic nerve for 2 min at 20 Hz in the rat evoked an attenuation of subsequent cardiac vagal action, which could be mimicked by exogenous NPY, but not GAL. The galanin antagonist, GAL1-13/NPY24-36, known to block the inhibitory action of galanin on the cardiac vagus in cats, did not alter the effect of sympathetic stimulation on cardiac vagal activity. We suggest on the basis of results here that in the rat, NPY released during stimulation of the cardiac sympathetic nerve, causes inhibition of acetylcholine release from the vagus nerve.

Anesthesia↗
PubMed1999

Diffusion-weighted magnetic resonance imaging of intracranial epidermoid tumours.

Intracranial epidermoids can closely mimic cerebrospinal fluid (CSF) on MRI and CT. Therefore epidermoids can be difficult to detect, or distinguish from CSF. Three cases of intracranial epidermoid are presented, one of which closely mimicked an arachnoid cyst on CT and routine MRI sequences. Diffusion-weighted magnetic resonance imaging (DWI) was performed. All three epidermoids demonstrated marked restriction of diffusion relative to CSF, clearly defining the extent of each lesion, and allowing differentiation from an arachnoid cyst or an enlarged CSF space.

Adult↗
PubMed1999

Effects of age on balance assessment using voluntary and involuntary step tasks.

BACKGROUND: Taking a step while standing and modifying a step while walking are two strategies often used to maintain balance when balance disturbances are encountered during activities of daily living. This study investigated whether performance on an involuntary step task, which is assumed to be a surrogate for fall recovery abilities, was comparable to performance on a voluntary step task. METHODS: The performance of a voluntary and an involuntary step task was measured in healthy young adult (mean age 21 years) and healthy elderly adult (mean age 68 years) female subjects. Subjects stepped as fast as possible in the direction of a minimally destabilizing lateral waist pull (voluntary step task), or they responded naturally to a large destabilizing lateral waist pull (involuntary step task). The effects of age, task, and their interaction on the primary outcome variables of step foot liftoff time, landing time, step length, and step height were examined. RESULTS: In the voluntary step task, the older adults, compared to the young, required significantly more time to lift their foot (Young: 307 msec; Elderly: 424 msec). In the involuntary step task, the elderly were as quick as the young in lifting their foot (Young: 322 msec; Elderly: 335 msec). The young lifted their foot at about the same time for the two tasks. The elders, on the other hand, lifted their foot significantly earlier in the involuntary step task, compared to the voluntary step task (Vol: 424 msec; Invol: 335 msec). CONCLUSIONS: A voluntary step task underestimates the ability of healthy elderly adults to respond quickly when large destabilizing balance disturbances are encountered.

Accidental Falls↗
PubMed1999

Brainstem dysfunction in chiari malformation presenting as profound hypoglycemia: presentation of four cases, review of the literature, and conjecture as to mechanism.

OBJECTIVE: We report four patients whose cases resulted in our observation that profound hypoglycemia resulting from intermittent hyperinsulinism plays a significant role in patients with brainstem dysfunction from Chiari I or II malformations who have intermittent autonomic dysfunction ("blue spells"). METHODS: The records of four children with severe brainstem dysfunction associated with hindbrain herniation (Chiari I or II malformation) were reviewed retrospectively. Each patient had severe lower cranial nerve dysfunction that required tracheotomy and feeding tube placement. After we found that profound hypoglycemia had occurred during a spell of autonomic dysfunction in one patient, the charts of the other three patients were reviewed for evidence of hypoglycemia. Now, whenever one of them has evidence of autonomic dysfunction, prospective studies of glucose and insulin levels are performed. Three of the patients had Chiari II malformation in association with myelomeningocele, and one patient had a Chiari I malformation resulting from Pfeiffer's syndrome. RESULTS: Hypoglycemia occurred in these patients episodically, and usually when their shunts were functioning. The hypoglycemia was associated with hyperinsulinemia in each patient. The brainstem structures of these children (presumably the dorsal motor nuclei of the vagus) were extremely sensitive to changes in local or regional intracranial pressure. These changes were triggered by intermittent shunt failure, agitation from pain, abdominal distention from constipation, and retention of CO2. In patients with Chiari malformations, even mild increases in intracranial pressure lead to brainstem dysfunction. One possible explanation is that pressure on the deformed Xth cranial nerve nuclei may lead to insulin release and life-threatening hypoglycemia. Continuous-drip feeds are necessary to prevent this complication. CONCLUSION: Patients with severe intermittent brainstem dysfunction after decompression of Chiari I or Chiari II malformations should have laboratory studies of glucose levels performed at the time of the episodes to rule out hypoglycemia.

Adolescent↗
PubMed1999

The stroke impact scale version 2.0. Evaluation of reliability, validity, and sensitivity to change.

BACKGROUND AND PURPOSE: To be useful for clinical research, an outcome measure must be feasible to administer and have sound psychometric attributes, including reliability, validity, and sensitivity to change. This study characterizes the psychometric properties of the Stroke Impact Scale (SIS) Version 2.0. METHODS: Version 2.0 of the SIS is a self-report measure that includes 64 items and assesses 8 domains (strength, hand function, ADL/IADL, mobility, communication, emotion, memory and thinking, and participation). Subjects with mild and moderate strokes completed the SIS at 1 month (n=91), at 3 months (n=80), and at 6 months after stroke (n=69). Twenty-five subjects had a replicate administration of the SIS 1 week after the 3-month or 6-month test. We evaluated internal consistency and test-retest reliability. The validity of the SIS domains was examined by comparing the SIS to existing stroke measures and by comparing differences in SIS scores across Rankin scale levels. The mixed model procedure was used to evaluate responsiveness of the SIS domain scores to change. RESULTS: Each of the 8 domains met or approached the standard of 0.9 alpha-coefficient for comparing the same patients across time. The intraclass correlation coefficients for test-retest reliability of SIS domains ranged from 0.70 to 0.92, except for the emotion domain (0.57). When the domains were compared with established outcome measures, the correlations were moderate to strong (0.44 to 0.84). The participation domain was most strongly associated with SF-36 social role function. SIS domain scores discriminated across 4 Rankin levels. SIS domains are responsive to change due to ongoing recovery. Responsiveness to change is affected by stroke severity and time since stroke. CONCLUSIONS: This new, stroke-specific outcome measure is reliable, valid, and sensitive to change. We are optimistic about the utility of measure. More studies are required to evaluate the SIS in larger and more heterogeneous populations and to evaluate the feasibility and validity of proxy responses for the most severely impaired patients.

Aged↗
PubMed1999

Motor evoked potentials in a rhesus macaque model of neuro-AIDS.

Previous work using bone marrow passaged SIVmac239 (simian immunodeficiency virus) has shown that macrophage tropic strains of this virus enter the rhesus macaque brain early following inoculation (Sharma et al, 1992; Desrosiers et al, 1991; Zhu et al, 1995; and Narayan et al, 1997). As part of an effort to more fully characterize the extent of neurologic impairment associated with SIV infection of the brain, we used transcranial electrical stimulation of motor cortex and the spinal cord to evoke EMG potentials in two forelimb (EDC and APB) and two hindlimb (LG and AH) muscles. The latencies, magnitudes and thresholds of motor evoked potentials (MEPs) recorded from nine monkeys infected with neurovirulent SIVmac R71/17E were compared to pre-inoculation records from the same monkeys. Seven of nine monkeys developed simian AIDS within 4 months of inoculation and were euthanized. Two monkeys remained free of AIDS-related clinical illness for over 18 months following inoculation. Six of the seven monkeys with rapidly progressing disease showed post-inoculation latency increases ( > or = 2 s.d. of control) in at least one cortical MEP. Increases in cortical MEP latency ranged from 21-97% in different monkeys. All seven rapidly progressing animals showed post-inoculation increases in at least one spinal cord MEP latency. Maximum spinal cord MEP latency increases ranged from 22-147%. Increases in central conduction time (CCT) ranged up to 204% and exceeded two standard deviations of control in four monkeys. Neither of the two monkeys with slowly progressing disease showed significant increases in either cortical or spinal cord MEP latency or CCT. Only the monkeys with rapidly progressing disease exhibited classic AIDS-related neuropathology, although there was no consistent relationship between the severity of neuropathology and the extent of MEP abnormalities. In conclusion, our results demonstrate clear deficits in the functional integrity of both central and peripheral motor system structures associated with SIV infection and further support the use of SIV-infected rhesus macaques as a model of neuro-AIDS.

Animals↗
PubMed1999

Development of a comprehensive assessment toolbox for stroke.

Comprehensive databases for the assessment of individuals with stroke are essential for clinical management and evaluation of outcomes for quality management and research. The purpose of this article is to describe a comprehensive data system or "toolbox" developed by clinicians and researchers at the Center on Aging at the University of Kansas Medical Center. The choice of assessments for the toolbox resulted from the Agency for Health Care Policy and Research Post-Stroke Rehabilitation Guidelines, results of the Kansas City Stroke Study, and the authors' work to develop a new stroke measure-the Stroke Impact Scale.

Aged↗
PubMed1998

The surgeon and casemix.

Casemix funding has markedly increased surgeons' awareness of the economies of the activities they undertake. Surgery has become a major focus at all large public hospitals, because of its high earning potential, and this pressure to maximise funding could influence surgical practice. Casemix funding's emphasis on length of hospital stay has encouraged forward planning for earlier discharge after surgical procedures. Patients are now assessed in pre-admission clinics, educated about their condition and their hospital stay, and a plan formulated for their discharge and rehabilitation. Funding for major surgical procedures of long duration in patients with complex conditions should reflect the higher level of resource utilisation. Tertiary referral centres, because of their commitment to training and research and their more severely ill patient population, are less cost-effective and require funding to ensure their viability. The improved information that casemix generates should be used to evaluate outcomes and improve patient care; efficiency must not take precedence over quality of care and compassion.

Australia↗
PubMed1998

Aqueous solubilization of transmembrane peptide sequences with retention of membrane insertion and function.

We recently reported that the peptide C-K4-M2GlyR mimics the action of chloride channels when incorporated into the apical membrane of cultured renal epithelial monolayers. C-K4-M2GlyR is one of a series of peptides that were prepared by the addition of lysine residues to the N- or C-terminus of the M2 transmembrane sequence of the brain glycine receptor. This study addresses how such modifications affect physical properties such as aqueous solubility, aggregation, and secondary structure, as well as the ability of the modified peptides to form channels in epithelial monolayers. A graded improvement in solubility with a concomitant decrease in aggregation in aqueous media was observed for the M2GlyR transmembrane sequences. Increases in short-circuit current (I(SC)) of epithelial monolayers were observed after treatment with some but not all of the peptides. The bioactivity was higher for the more soluble, less aggregated M2GlyR peptides. As described in our previous communication, sensitivity of channel activity to diphenylamine-2-carboxylate, a chloride channel blocker, and bumetanide, an inhibitor of the Na/K/2Cl cotransporter, was used to assess changes in chloride selectivity for the different assembled channel-forming peptides. The unmodified M2GlyR sequence and the modified peptides with less positive charge are more sensitive to these agents than are the more highly charged forms. This study shows that relatively insoluble transmembrane sequences can be modified such that they are easier to purify and deliver in the absence of organic solvents with retention of membrane association, insertion, and assembly.

Amino Acid Sequence↗