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Biomedical subjects

D L Jackson

Publications and source records attributed to D L Jackson.

At least 37 records · Page 2Linked to original sources
PubMed1994

Identification of myelin-associated glycoprotein as a major myelin-derived inhibitor of neurite growth.

Contact-dependent axon growth inhibitory activity is present in CNS myelin, but the inhibitory proteins have not been fully characterized. We report here that at least two peaks of inhibitory activity can be separated by fractionating solubilized CNS myelin proteins by DEAE chromatography. A major peak of inhibitory activity corresponded to the elution profile of myelin-associated glycoprotein (MAG). Immunodepletion of MAG from these inhibitory fractions removed neurite growth inhibition, whereas recombinant MAG (ectodomain) was a potent inhibitor of neurite outgrowth. Immunodepletion of MAG from total extracts of CNS myelin restored neurite growth up to 63% of control levels. These results establish that MAG is a significant, and possibly the major, inhibitor in CNS myelin; this has broad implications for axonal regeneration in the injured mammalian CNS.

Animals↗
PubMed1992

Tarsal tunnel syndrome in runners.

Tarsal tunnel syndrome has only recently been noted to be a cause of foot and ankle pain in runners. The tarsal tunnel is located just posterior to the medial malleolus and may compress the posterior tibial nerve as it passes through it, producing numbness and paraesthesia in the foot. While the aetiology of this condition is frequently multifactorial, abnormal foot and ankle mechanics and excessive training tend to be the most commonly cited aetiological factors. Successful treatment of tarsal tunnel syndrome requires an accurate diagnosis by differentiating it from plantar fasciitis and Achilles tendinitis and then making proper biomechanical and training changes in the runner. Conservative treatment is generally successful, but occasionally surgical treatment is required to decompress the nerve.

Diagnosis, Differential↗
PubMed1989

Preoperative nonsteroidal anti-inflammatory medication for the prevention of postoperative dental pain.

It is predictable for patients to experience postoperative pain and inflammation. Until recently, therapeutic strategies for the management of these sequelae have been symptomatic rather than preventive. This article reviews prophylactic use of nonsteroidal anti-inflammatory medication for preventing postoperative discomfort, and includes recommendations on patient selection and medication regiment.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1989

Fractures in the men of a Veterans Administration Nursing Home: relation to 1,25-dihydroxyvitamin D.

One hundred fifty-three men, age 48-96, 86% white, had resided in this Nursing Home for an average of 6.3 years (range 1.3-36) as of August 1984. At that time, we reviewed their medical charts to record the numbers and sites of fractures which had been diagnosed during the preceding 1 to 5 years of Nursing Home residence, the duration of this period depending on the duration of institutionalization. In addition, a clinical database was compiled comprising 70 attributes, including diagnoses, drugs, plasma (serum) chemistries, and measures of hematologic, nutritional, and functional status. Fractures during the studied period of Nursing Home residence had occurred in 24 of 153 men; six residents had experienced two or more fractures. Fracture rates in hip, spine, and wrist were 2564, 366, and 549 per 100,000 patient years, respectively. The total fracture rate, hip fracture rate, and limb fracture rate were five to 11 times higher than in the age-matched general population of white men in the United States; in Rochester, MN; in Dundee, England; in Oxford, England; or in Finland. Univariate statistical analysis showed that the rates for hip fracture or for fracture at any site were significantly associated with 13 attributes: directly with age, plasma somatomedin C, blood urea N, serum creatinine, serum uric acid, serum 25-hydroxyvitamin D (25-OH-D), degree of functional impairment, and chronic urinary tract infection, and inversely with serum 1,25-dihydroxyvitamin D [1,25-(OH)2-D], serum albumin, hematocrit, and hemoglobin. There was not a significant correlation with the number of falls/month which occurred during the 7 months after August 1984. After the effect of age was partialed out, somatomedin C, 25-OH-D, 1,25-(OH)2-D, and the diagnosis of urinary tract infection were still significantly related to the occurrence of fractures. The fact that Nursing Home fracture cases had significantly higher blood urea nitrogen and 25-OH-D, and significantly lower 1,25-(OH)2-D, than their non-fracture counterparts suggests that impaired renal production of the latter vitamin D metabolite contributed to the excessive rate of fractures.

Adult↗
PubMed1988

No correlation between cerebral blood flow and neurologic recovery after reversible total cerebral ischemia in the dog.

This study was conducted to determine if regional cerebral flow during the first day after total cerebral ischemia was correlated with neurologic deficit and eventual survival. Dogs were subjected to 11 min of total cerebral ischemia (TCI) produced by an arterial and venous double balloon occlusion method. Recovery was allowed for up to 7 days after reperfusion, whereupon it was reassessed in survivors. Blood flow, determined by the radiolabeled microsphere method, was determined before TCI and at times up to 24 h after reperfusion. Blood flow during reperfusion after TCI followed the expected pattern of immediate hyperperfusion followed by prolonged hypoperfusion. TCI of 11 min duration resulted in a 50% mortality rate by 1 week. No positive correlation between magnitude or duration of hypoperfusion and neurologic deficit or mortality was found. It was concluded that improved postischemic blood flow cannot be used as a criterion for assessing drug therapy without reference to metabolic demand. The observation of a statistical correlation between dogs that survived and lower hematocrit was reported. It was suggested that the prolonged hypoperfusion encountered after TCI was not pathological, but rather served as a mechanism to limit oxygen exposure to the brain during a vulnerable period and, thus, was part of a controlled attempt at recovery of function by the central nervous system.

Animals↗
PubMed1988

Plasma testosterone in nursing home men.

Plasma testosterone (T) was measured at 8-9 a.m. in 44 men chronically institutionalized in a Veterans Administration Nursing Home, and correlated with an extensive clinical data base (including age, diagnoses, drugs, laboratory tests, anthropometric measurements, and mortality during the year after the T analysis). Age averaged 76.4 years (range 60-95). Plasma T was below the lower limit of the normal range for healthy young men (i.e. less than 300 ng/dl) in 46% of the men studied. Samples containing low T (less than 300 ng/dl) also contained subnormal unbound T, but normal concentrations of thyroxine and cortisol. Of the low T samples, 45% contained elevated LH, FSH or both (over 20 mU/ml), and the remaining 55% contained LH and FSH levels below this threshold, these two subgroups representing peripheral and central hypogonadism respectively. Plasma T was significantly (p less than 0.02) correlated in a direct relationship with hemoglobin, serum cholesterol, and the occurrence of seizures.

Aged↗
PubMed1987

Subnormal concentrations of serum selenium and plasma carnitine in chronically tube-fed patients.

Forty-seven tube-fed nursing home patients were investigated with regard to serum or plasma selenium (Se), carnitine, and red blood cell (RBC) glutathione peroxidase (GSH-Px). Thirty-six patients were tube fed with Isocal, and 11 were tube fed with Compleat B, an L-carnitine-containing formula. Eighteen elderly nursing home patients and 10 young adults served as controls. Serum Se and plasma carnitine were lowest (p less than 0.05) in the Isocal patients. In all 36 Isocal subjects, Se was below normal, and in 26% of Isocal patients RBC GSH-Px was also below normal. Free and total carnitine were below normal in most Isocal subjects. All 11 Compleat B patients had subnormal serum Se, but most had normal carnitine concentrations. These data suggest that enteral formulae in nursing homes should contain greater than 100 micrograms Se and on the order of a mmol carnitine/1600 kcal.

Adult↗
PubMed1987

Antecedents of death in the men of a Veterans Administration nursing home.

This study aims to learn whether the annual clinical and laboratory screening of nursing home residents provides significant information about their chance of dying during the following year. In August 1984, a comprehensive clinical data base was compiled for 176 male residents of this VA nursing home. During the next 14 months, 12 men were discharged to other locations and were dropped from the study; among the remaining 166, who comprised the study group of this report, 24 died. The most common immediate causes of death were infections (67%) and cardiac disorders (25%). Twenty of the deaths occurred after transfer to the acute hospital services. Among the 67 items in the clinical data base (including absence or presence of 17 diagnoses and 16 drugs), eight were significantly correlated with death rate. Age and functional impairment were directly related, and inversely related were the following: body weight as percent of ideal, triceps skin fold, hematocrit, hemoglobin, serum albumin, and serum cholesterol. Multivariate analysis showed cholesterol and hematocrit to be the most informative of the eight mortality predictors and to correlate with death independently of age and functional level. Subgroups defined on the basis of combinations of mortality-related attributes differed many fold in their death rates. For example, men with cholesterol less than or equal to 156 mg/dl and hematocrit less than or equal to 41% died at a rate 42 times the rate of men with values above both thresholds. For each mortality-related attribute, death rate varied with the level of the attribute. This relationship extended into the generally accepted "normal ranges" for cholesterol, hematocrit, hemoglobin, and albumin.

Aged↗
PubMed1987

Hyposomatomedinemia in the men of a Veterans Administration Nursing Home: prevalence and correlates.

A previous study found hyposomatomedinemia to be common in the men of this VA Nursing Home. To gain information on the prevalence and correlates of this endocrine characteristic, we have measured plasma somatomedin C (SmC) in 69 Nursing Home men 55-95 years old (group I), and in 37 independent men 56-87 years old attending our geriatric medicine outpatient clinic (group II). In groups I and II, a clinical data base was compiled comprising: blood chemistries, measures of body composition - nutritional state and functional level, diagnoses, medications, and morbidity and mortality during the year after the SmC analysis. The mean +/- SD for SmC was significantly (p less than 0.05) lower in group I (0.35 +/- 0.21 units/ml) than in group II (0.45 +/- 0.13 units/ml). SmC less than 0.25 units/ml, a range consistent with severe growth hormone deficiency, was found almost exclusively in group I (31.8% of men in group I, 3.7% of men in group II). In either group I, or in groups I and II combined, SmC was significantly (p less than 0.05) correlated with body weight as percentage of ideal, midarm muscle circumference (MAMC) as percent of standard, diagnosis of cerebrovascular disease, and plasma testosterone level. Men with SmC values below 0.25 units/ml had significantly (p less than 0.05) lower values for body weight as percentage of ideal, and for MAMC as percentage of standard. Except for cerebrovascular disease, SmC did not correlate significantly (p greater than 0.05) with diagnosis, drugs, morbidity or mortality.

Aged↗
PubMed1985

Profile of medical ICU vs. ward patients in an acute care hospital.

Demographic characteristics, severity of illness, resource utilization, and outcome were compared for 351 medical ICU (MICU) and 329 ward patients of a large, urban, tertiary care hospital. Patients were similar in age, race, sex, and insurance coverage. Both MICU and ward patients had similar health status distributions 3 to 6 months before hospitalization. Severity of illness, as measured by the Acute Physiology Score was significantly higher in the MICU patients, although there was considerable overlap in the distributions. Resource utilization, as measured by the Therapeutic Intervention Scoring System (TISS), was also significantly higher in the MICU; again, the distributions of the two groups overlapped, although mostly for low values of TISS. Of the MICU sample, 28% to 30% never required active therapeutic interventions; 11% of the ward sample received active treatment. The significant overlap between MICU and ward distributions of severity of illness and resource utilization has implications for admission and discharge policies.

Delivery of Health Care↗
PubMed1985

Simultaneous measurements of cerebral blood flow by the xenon/CT method and the microsphere method. A comparison.

Simultaneous measurements of cerebral blood flow have been performed in baboons to assess the correlation between the acute and invasive nondiffusible microsphere technique and the noninvasive xenon-enhanced CT method. Blood flows in small tissue volumes (approximately 1 cm3) were directly compared. The results of these studies demonstrate a statistically significant association between the two methods (P less than .001). Similar correlations were obtained by both the Kendall tau (tau) and the Spearman (r) methods. The problems and limitations of such correlations are discussed.

Animals↗
PubMed1985

Implications of DRG payments for medical intensive care.

Patients in the most prevalent DRGs in a Medical Intensive Care Unit (MICU) were compared with their counterparts who received only routine hospital care on adjusted total hospital costs and length of stay. Costs for both groups were compared with estimated DRG payments under an all-payer system. For patients in three DRGs, measures of severity of illness were examined as predictors of costs. Significant differences between MICU and routine care patients were found in 10 of 13 DRGs studied; intensive care costs were substantially above overall payment rates. The severity of illness measures varied widely in their correlation with costs, depending on DRG and whether the patients were MICU or routine care. These apparent differences in accounting costs may result in hospital decisions to restrict the number of MICU beds. Severity of illness adjustments to DRGs might produce more equitable payments. The most useful measure of severity may differ, however, depending on DRG.

Aged↗
PubMed1984

Total cerebral ischemia: effect of alterations in arterial PCO2 on cerebral microcirculation.

Radiolabeled 15-microns microspheres were used to examine alterations in regional CBF and cerebrovascular resistance in response to changes in arterial PCO2. Flow measurements were obtained before and 1-3 and 24 h after 12 min of total cerebral ischemia. Striking sensitivity of blood flow in all areas of the central nervous system was shown to changes in arterial PCO2 between 24 and 50 mm Hg during the control nonischemic period. Following 12 min of total cerebral ischemia, cerebrovascular resistance increased, producing a decrease in regional blood flow when the important controlling variables for CBF were held constant. One to 3 h after total cerebral ischemia, the effect of variations in arterial PCO2 on cerebral blood flow was almost completely abolished. Within 24 h after total cerebral ischemia, the sensitivity of CBF to changes in PCO2 was almost completely restored, whereas the secondary severe neurologic deficit remained. Therapeutic interventions following global cerebral ischemia, designed to ameliorate the "no-reflow" phenomenon and minimize residual ischemic neurologic damage, must take into account this marked early post-ischemic reduction in sensitivity to normally potent cerebrovasodilatory influences.

Animals↗