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Biomedical subjects

T G Nick

Publications and source records attributed to T G Nick.

At least 19 recordsLinked to original sources
PubMed2002

Effect of estrogen deficiency on skeletal and alveolar bone density in sheep.

BACKGROUND: This study provides a longitudinal assessment of changes in alveolar and skeletal bone mineral density (BMD) in ovariectomized animals. METHODS: Following ovariectomy (OVX) (n = 6) or sham-operation (n = 6) intraoral radiographs were made at 4-month intervals and serum 17-beta-estradiol, osteocalcin, and interleukin (IL)-6, urinary deoxypyridinium, and salivary IL-6, deoxypyridinium, and osteocalcin concentrations were evaluated. Twelve months after surgery, animals were sacrificed and the mandible and radius/ulna removed. Bones were sectioned and radiographed. Mean BMD and cortical thicknesses were calculated from each region. RESULTS: OVX animals had a progressive decrease in serum 17-beta-estradiol, increased serum osteocalcin and IL-6, urinary deoxypyridinium and salivary IL-6, osteocalcin and deoxypyridinium (P < 0.001), suggesting that they were becoming osteoporotic. The BMD of the radius/ulna and mandibular alveolar bone was significantly reduced in OVX animals (P < 0.05 and P < 0.001, respectively). Reduced alveolar bone BMD became evident in OVX animals 6 months after surgery and became more severe during the subsequent 6 months. Alveolar crestal height was also significantly reduced in OVX animals (P < 0.001). These biochemical and density changes preceded a significant reduction in serum 17-beta-estradiol, which occurred between 4 and 8 months following surgery. CONCLUSIONS: Serial measurements of alveolar BMD predicts loss of skeletal BMD in OVX sheep. Changes in alveolar BMD precede estrogen deficiency, suggesting that early signs of reduced BMD may be detected in peri-menopausal women. The presence of biomarkers of bone metabolism within saliva and their correlation with reduced BMD suggests that saliva could be used as an adjunct screening method for assessment of skeletal bone density.

Alveolar Process↗
PubMed2001

Long-term neuropsychological outcome after traumatic brain injury.

OBJECTIVE: To describe neuropsychological outcome 5 years after injury in persons with traumatic brain injury (TBI) who received inpatient medical rehabilitation. To determine the magnitude and pattern neuropsychological recovery from 1 year to 5 years after injury. DESIGN: Longitudinal cohort study with inclusion based on the availability of neuropsychological data at 1 year and 5 years after injury. SETTING: National Institute on Disability and Rehabilitation Research Traumatic Brain Injury Model Systems of Care. PARTICIPANTS: One hundred eighty-two persons with complicated mild to severe traumatic brain injury. PRIMARY OUTCOME MEASURES: Digits Forward and Backward, Logical Memory I and II, Token Test, Controlled Oral Word Association Test, Symbol Digit Modalities Test, Trail Making Test, Rey Auditory Verbal Learning Test, Visual Form Discrimination, Block Design, Wisconsin Card Sorting Test, and Grooved Pegboard. RESULTS: Significant variability in outcome was found 5 years after TBI, ranging from no measurable impairment to severe impairment on neuropsychological tests. Improvement from 1 year after injury to 5 years was also variable. Using the Reliable Change Index, 22.2% improved, 15.2% declined, and 62.6% were unchanged on test measures. CONCLUSIONS: Neuropsychological recovery after TBI is not uniform across individuals and neuropsychological domains. For a subset of persons with moderate to severe TBI, neuropsychological recovery may continue several years after injury with substantial recovery. For other persons, measurable impairment remains 5 years after injury. Improvement was most apparent on measures of cognitive speed, visuoconstruction, and verbal memory.

Adult↗
PubMed2000

The effect of prior hypothermia on the physiological response to norepinephrine.

OBJECTIVE: this study determines the effect of prior hypothermia on the cardiovascular responses to norepinephrine (NE) after rewarming. METHODS: the experiment was a 2x2 controlled design with four groups of feline animals. The two variables were the presence or absence of previous cooling, and the use or non-use of NE after rewarming. During the 'cooling' phase, animals were either cooled using an external arterial-venous femoral shunt to 30 degrees C or maintained at 37 degrees C. After 'rewarming' animals were stratified to receive either NE at rates to deliver 0.2, 1.0 or 5 microg/kg per h or normal saline infusions. Animals were instrumented to measure mean arterial pressure (MAP) and cardiac output (CO) and systemic vascular resistance (SVR) was calculated. RESULTS: there were no differences between groups at baseline and low dose NE (0.2 microg/kg per min). At 1.0 microg/kg per min, NE caused a significant increase in CO (P<0.01) and no effect of MAP or SVR in the rewarmed animals when compared with normothermic controls. In rewarmed animals 5.0 microg/kg per min NE caused a significant increase in CO (P<0.01) and no effect on MAP or SVR. In normothermic controls there was a significant increase in SVR (P=0.02) and MAP (P=0.05) and no effect on CO. CONCLUSION: this study shows that the effect of prior hypothermia on cardiovascular responses to moderate and high doses of NE is an improved CO with no affect on SVR and MAP. This could alter the clinical utility of NE in this situation.

Animals↗
PubMed2000

Retinoic acid inhibition of cardiac mesenchyme formation in vitro correlates with changes in the secretion of particulate matrix from the myocardium.

Retinoic acid has been associated with a variety of cardiac defects. A percentage of these defects are related to changes in the endocardial cushions. Studies in mice and older chick embryos have shown a decrease in mesenchymal cell formation attributable to retinoic acid and have suggested that retinoic acid was affecting the extracellular matrix. In this study we have tested the effect of retinoic acid on cardiac mesenchyme formation in vitro and then tested retinoic acid treated myocyte cultures for changes in the expression of hLAMP-1, fibronectin and transferrin members of the particulate matrix that is required for mesenchyme formation. Initial experiments tested the effect of retinoic acid on mesenchymal cell formation first in atrioventricular canal and outflow tract explant cultures and then in AV endothelial monolayer cultures using myocyte conditioned media or the particulate matrix fraction from retinoic acid treated myocyte cultures. In all cases, mesenchymal cell formation was suppressed while no suppression was observed when MyoCM was included with retinoic acid. Protein analysis showed that retinoic acid had a stimulatory effect on protein synthesis. ELISA assays revealed that retinoic acid treated myocyte cultures contained significantly more hLAMP-1 and fibronectin than either normal or DMSO controls. However, transferrin was not affected by retinoic acid treatment in these experiments. Our results suggest that retinoic acid affects the expression of the particulate matrix and that these changes may be responsible for the observed decrease in mesenchymal cell formation.

Animals↗
PubMed2000

EMT domestic violence knowledge and the results of an educational intervention.

The objective of this study was to determine levels of knowledge regarding domestic violence (DV), and the effectiveness of formal instruction about DV. A general knowledge survey of DV was given before and approximately 4 to 6 months after 3 hours of instruction given by Emergency Medicine and Law Enforcement faculty. A Emergency medical service (EMS) consisting of 73% paramedic-level providers in a metropolitan urban/suburban area. Differences in DV knowledge before and after the instruction were the main outcome measures. In the preinstruction series, 46 emergency medical technicians (EMTs) participated. After the instruction 19 EMTs participated (42%). Thirty-five percent of EMTs before instruction and 37% after instruction correctly identified the prevalence of DV against women as 15% to 30%. Thirty-five percent of EMTs before instruction and 63% after instruction (P < .05) correctly identified the prevalence of DV against men as 0% to 15%. Before instruction 54% knew that DV is equal among races, and 79% after instruction (P < .05). Before instruction 37% of EMTs knew that DV is equal in different socioeconomic groups and 68% after instruction (P < .05). The percent of EMTs who knew that the victim is not responsible for the abuse was 50% before instruction and 89% after instruction (P < .05). Before instruction, the results on a knowledge questionnaire were 54% correct, after instruction, results improved to 71% correct. Improvement in understanding of DV was shown for 4 of 11 questions after 3 hours of instruction. These results indicate the need for more instruction on DV for EMTs.

Adult↗
PubMed2000

Breast cancer knowledge and preventive behaviors: An urban emergency department-based survey.

OBJECTIVE: To assess general knowledge and preventive behaviors regarding breast cancer among women who present to an urban emergency department. METHODS: During a six-month study period, a convenience sampling of women aged 21 years and older who were in treatment and waiting areas was surveyed. The anonymous written survey asked about demographic variables, knowledge, and preventive behaviors regarding breast cancer. Knowledge was assessed with questions about the recommended frequency of breast self-examination and the recommended age for first mammography. Performance was assessed by questions about breast self-exam and mammography. Subgroup analysis was done by age (above and below 40 years old), race, income (above and below the median), insurance type, history of breast lump, and family history (FH) of breast cancer. RESULTS: Four hundred women completed surveys. Two hundred twelve (53%) correctly knew the answers to the two knowledge questions. Knowledge was greater in women with private insurance. Knowledge of the frequency of breast self-exam was significantly greater among whites and Native Americans than among African Americans, Asians, or Hispanics. Stated performance of preventive behaviors was 72% (288) for breast self-exam and for mammography. Preventive behaviors were significantly more likely to be performed by higher-income and privately-insured women. Breast self-exam was more likely to be done in older women, those with a history of a breast lump, and those with a FH of breast cancer. CONCLUSIONS: Women with lower income and without private insurance were less likely to be knowledgeable and practice preventive measures for detecting breast disease.

Adult↗
PubMed2000

Domestic violence in a university emergency department.

BACKGROUND: We attempted to determine the prevalence and demographics of domestic violence (DV) among male and female patients in a university emergency department (ED). METHODS: The validated Index of Spouse Abuse (ISA) was used. Patients aged 18 years or older seen during 28 randomly selected 4-hour shifts were eligible. RESULTS: Of the 97 participants in the study, 57 were female. One man and 3 women were victims of present physical DV, with 1 male and 2 female victims of present nonphysical abuse. Three of the 40 men and 22 of the 57 women had been victims of past physical violence. One man and 15 women had been victims of past nonphysical abuse. Alcohol use, suicidal ideation, family history, and psychiatric history were all strongly correlated with DV. CONCLUSIONS: The prevalence of DV past was significantly higher in the females. Present violence was more rare and less than that reported in other ED studies.

Adult↗
PubMed1999

Usefulness of the blood urea nitrogen/creatinine ratio in gastrointestinal bleeding.

This study was conducted to evaluate the blood urea nitrogen/creatinine (BUN/Cr) ratio for distinguishing an upper versus lower source of gastrointestinal (GI) bleeding. Charts of patients who presented to the emergency department (ED) with the diagnosis of GI bleeding from August 1995 to August 1996 were retrospectively reviewed for source of bleeding, initial BUN, Cr, BUN/Cr ratio, hematocrit (Hct), and need for transfusion. A total of 124 patients were eligible for inclusion, 71 (57%) of whom were male. A total of 63 (51%) presented with blood in stool and 53 (43%) with bloody emesis; 8 (6%) had blood in both emesis and stool. A total of 31 (25%) patients had a lower GI bleed, 88 (70%) had an upper, and 5 (4%) had both upper and lower bleeding sources. The mean BUN level was 24 mg/dL, the mean Cr level 1.03 mg/dL, and the mean BUN/Cr ratio was 24. The mean hemoglobin (Hb) level was 11.3 g/dL, the mean Hct was 32 g/dL, and 51% required transfusion. Upper GI bleeding was significantly correlated with age younger than 50 (P = .01) and male gender (P = .01; odds ratio, 3.13). Taking into account age and gender, the BUN/Cr ratio correlated significantly with an upper GI source of bleeding (P = .03), with a ratio greater than 36 having a sensitivity of 90% and a specificity of 27%. The area under the receiver operating characteristic curve using age, gender, and BUN/Cr ratio was .73 (95% confidence interval, .62 to .84).

Age Distribution↗
PubMed1999

Contribution of functional ratings to prediction of longterm employment outcome after traumatic brain injury.

The present study investigated the contribution of functional ratings to prediction of employment outcome after traumatic brain injury (TBI). Previous studies have suggested that functional ratings obtained at a significant time post-injury can supplement neurologic, pre-injury, neuropsychologic, and other post-injury variables in predicting long-term employment outcome. Functional ratings studied were patients' needs for physical, cognitive, and behavioural supervision. This investigation also addressed the issue of predicting long-term outcome for the select group of TBI patients who receive post-acute brain injury rehabilitation. Subjects were 76 patients with TBI. The mean age (25th, 50th, and 75th percentiles) was 32 (22, 28, 39) years and mean premorbid education level was 13 (12, 12, 14) years. Predictors studied were severity of injury, premorbid education level, pre-injury substance use, and needs for physical, cognitive and behavioural supervision at discharge from post-acute rehabilitation. Supervision needs ratings were obtained an average of 9.6 (4.2, 5.9, 11.2) months post-injury. Productivity status was assessed an average of 22.5 (12.6, 20.7, 30.5) months post-injury and 12.9 (4.9, 12.4, 16.6) months post-discharge from treatment. Spearman correlation coefficients revealed that premorbid educational level, pre-injury substance use, and needs for physical and behavioural supervision were related to long-term functional outcome (p < 0.05). However, multiple logistic regression analysis revealed that only level of pre-injury substance use was predictive of long-term productivity outcome once adjusted for the effects of the other predictors. Patients with no history of pre-injury substance use were more than eight times as likely to be employed at follow-up as those with a history of pre-injury substance abuse (p < 0.01).

Adult↗
PubMed1998

Impaired awareness and employment outcome after traumatic brain injury.

Inaccurate self-awareness is a common finding after traumatic brain injury. Such impaired awareness has been hypothesized to limit patients' eventual functional outcomes by decreasing motivation for treatment and resulting in selection of inappropriate long-term goals. Previous investigations of the association between impaired awareness and employment outcome have produced inconsistent results. The present article reviews these studies and presents the results of our new investigation of this issue. In addition, we studied the comparability of two methods of measuring impaired awareness. Results provided strong support for a positive relationship between accurate self-awareness and favorable employment outcome at follow-up.

Adolescent↗
PubMed1998

Domestic violence awareness and prevalence in a first-year medical school class.

OBJECTIVE: To determine knowledge about domestic violence (DV), the effectiveness of formal instruction about DV, and the prevalence of DV in a first-year medical school class. METHODS: A general-knowledge survey of DV was given before and approximately 1 month after 3 hours of instruction provided by emergency medicine and internal medicine faculty. A previously validated scale, the Index of Spouse Abuse (ISA), was offered to determine baseline levels, of DV within the group. Differences in first-year medical student knowledge of facts about DV and differences in responses by men vs women were determined before and after the instruction. RESULTS: In the pre-instruction series, 144 of 148 (97%) participated. After the instruction, 141 of the same 148 students participated (95%). The prevalence of DV against women was correctly identified by 45% of the students as "15-30%" prior to instruction, and 65% after instruction. The prevalence of DV against males was correctly identified as "0-15%" by 48% of the students prior to instruction, and 70% after instruction. Before instruction, 29% of the students knew that "DV rates are equal in different socioeconomic groups," vs 72% after instruction. Similarly, prior to instruction 58% of the students knew that the victim is not responsible for the abuse, and 84% knew this after instruction. Before instruction 14 (10%) of the students believed they were victims of DV in the past, representing 7% of the men and 13% of the women. Before instruction neither group believed they were present victims of DV. However, according to ISA scoring, 6% of the women were positive for violence in the past, and approximately 5% were positive for present violence. No men were positive for ISA-determined past or present violence. CONCLUSION: Improvement in awareness was demonstrated after 3 hours of instruction in a first-year medical school class. There was DV among female medical students in this first-year class and self-reporting was not reliable. These results support instruction on DV for medical students.

Adult↗
PubMed1998

Descriptive and graphical strategies for assessing change: a case study of functional status in stroke patients.

A primary focus in the current context of the health care industry is the measurement of outcomes. Outcomes research, although inclusive of the use of advanced statistical analyses, can often be conducted using more easily understood analytical techniques such as descriptive analysis and graphical display of data. The article addresses the description and analysis of patient change scores on the Functional Independence Measure (FIM) from 745 stroke rehabilitation inpatients. Display and discussion of percentiles, cross-tabulations, scatter plots, and side-by-side box plots are used in this case study of describing outcomes.

Activities of Daily Living↗
PubMed1997

Domestic violence in an inner-city ED.

STUDY OBJECTIVE: To determine the prevalence of domestic violence (DV) for male and female ED patients and to determine the demographics of DV. METHODS: The study design was a descriptive written survey of adults. We used the Index of Spouse Abuse (ISA), a previously validated survey tool. The study was set in an inner-city ED with approximately 75,000 patients annually, most of them indigent. Patients 18 years or older who were able to give consent were included. Patients were excluded if they had a language barrier, were a prisoner, or had never had a partner. All patients presenting during 31 randomly selected 4-hour shifts during July 1995 were considered for the study. DV was defined as either physical or nonphysical on the basis of ISA scoring. The prevalence was determined for present (in the preceding year) and past (more than 1 year ago) abuse. Four violence parameters were calculated for patients who had a partner at the time of presentation: present physical, present nonphysical, past physical, and past nonphysical. Only the "past" parameters were calculated for patients who had had a partner in the past but had no partner at the time of presentation. We used the chi2 test to determine individually significant predictors of the four parameters. Logistic-regression models were constructed to determine the significant predictors of DV. Associations among the present physical, present nonphysical, past physical, and past nonphysical abuse categories were determined with McNemar's test. RESULTS: We enrolled 516 patients, 233 men and 283 women. On the basis of ISA scoring, 14% of men and 22% of women had experienced past nonphysical violence (P=.02, men versus women), and 28% of men and 33% of women had experienced past physical violence (P=.35). Of the 157 men and 207 women with partners at the time of presentation, 11% of men and 15% of women reported present nonphysical violence (P=.20), and 20% men and 19% of women reported present physical violence (P=.71). Using logistic-regression models, we determined that women experienced significantly more past and present nonphysical violence but not physical violence than men. For all four parameters, the victim's suicidal ideation and alcohol use were independently associated with DV. The victim's family history was strongly associated with past abuse. Using McNemar's test, we found that physical and nonphysical abuse were correlated in the past and present. CONCLUSION: Using a validated scale, we found that the prevalences of physical DV for men and women are high and that they are not statistically different in this population. Using chi 2 testing, we found that women had experienced significantly more past nonphysical violence than men; using logistic regression we found that they experienced significantly more nonphysical violence (both past and present) than men. DV was frequently associated with suicidal ideation, alcohol use, and family history of violence.

Adolescent↗
PubMed1997

Testing for treatment effect in the presence of regression toward the mean.

We are often faced with the statistical problem of evaluating the effect of a treatment in the extreme of a population. This requires taking measurements on truncated random variables and, hence, it becomes necessary to take proper account of the effect of regression toward the mean. The usual statistical procedures are inappropriate for testing treatment effect in the presence of regression toward the mean. Likelihood ratio and score tests based on truncated distributions should provide valid statistical inferences in these situations. We conducted simulation studies to investigate the properties of these methods and found that the likelihood ratio test performs well even when the sample size is moderate, whereas the score test does not seem to control the nominal significance level. We compared the likelihood ratio test to a regression-based t-test, assuming the mean of the baseline distribution to be known, and found the likelihood ratio test more powerful. In the case where the baseline mean is unknown, we also investigated Wald's test and compared it with the likelihood ratio test and score test with respect to validity and power using simulation. Wald's test and the score test do not control the nominal significance level unless the sample size is extremely large. Overall, the likelihood ratio test has the best performance among all the methods studied. The proposed likelihood ratio test is illustrated using an example of a cholesterol study.

Biometry↗