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Biomedical subjects

D L Jackson

Publications and source records attributed to D L Jackson.

64 records · Page 4Linked to original sources
PubMedDate not supplied

Total cerebral ischemia: application of a new model system to studies of cerebral microcirculation.

Reduction in cerebral blood flow (CBF) following global ischemia has been implicated as a pathogenetic mechanism in progressive brain damage seen after restoration of effective cardiac action and cerebral perfusion pressure. There are serious limitations to many of the techniques for measuring regional cerebral blood flow, particularly during low flow states. In 15 dogs anesthetized with thiopental, 12 minutes of total cerebral ischemia (TCI) was produced using a double balloon occlusion technique. Total and regional cerebral blood flows were sequentially measured before and after balloon release by left ventricular injection of 15 mu microspheres labelled with 5 different radionuclides. Total CBF was reduced 53 +/- 5% (mean +/- SEM) from pre-ischemic values between 1 and 3 hours after "resuscitation" despite normal perfusion pressure and arterial blood gases. CBF remained slightly reduced (24 +/- 7%) at 6 hours post-ischemia. Thirty minutes after balloon release, grey matter flow was reduced 38 +/- 8% from control values while adjacent white matter flow was increased 21 +/- 10%. However, by 1 hour after ischemia, grey and white matter flows were both reduced (60 +/- 3%, 41 +/- 5% respectively). Similar differences in brain stem and cerebellar flow were also observed. The majority (71-86%) of the reduction in total CBF seen at one hour post-TCI is due to increased cerebrovascular resistance, with 14-29% of the decrease related to arteriovenous shunting.

Animals↗
PubMedDate not supplied

Clinical experience with the use of xenon-enhanced CT blood flow mapping in cerebral vascular disease.

Cerebral blood flow mapping with the xenon-enhanced/CT method has become a useful clinical tool in the management of patients with occlusive cerebral vascular disease. Studies involving 4-5 minutes of inhaling a xenon/oxygen mixture (less than or equal to 35%) can now be performed routinely with acceptable patient tolerance and compliance. Four cases with acute and chronic ischemic injuries are reported here to illustrate the manner in which this method has been used to characterize flow pattern in such patients and the relevance of this flow information to clinical patient management.

Adult↗
PubMedDate not supplied

Measurement of cerebral blood flow during xenon inhalation as measured by the microspheres method.

Measurements of cerebral blood flow (CBF) were performed using the microsphere technique in non-human primates (baboons) to assess the effect of non-radioactive xenon gas inhalation on CBF. Blood flows in small tissue volumes (approximately 1 cm3) were directly measured before and during the inhalation of xenon/oxygen gas mixtures. The results of these studies demonstrated that when inhaled in relatively high concentrations, xenon gas does increase CBF, but the changes are more global than tissue-specific. The problems and limitations of such evaluations are discussed.

Animals↗
PubMedDate not supplied

Relation of serum albumin concentration to death rate in nursing home men.

Serum albumin was measured in 126 men (average age 70.6; range 40 to 96) of a Veterans Administration Nursing Home, and was correlated with other items in an extensive clinical data base, including death or survival during the year after the analysis. The reason for institutionalization was chronic neurologic disease or other disabling physical condition in 63 men (group A), and psychiatric disorder in 63 men (group B). In group A, the proportions of men with albumin less than 3.5, 3.5-4.0, and greater than 4.0 g/dl were 6%, 37%, and 57%, respectively. In this group, the serum albumin level was significantly (p less than 0.05) correlated with death rate, hemoglobin, hematocrit, serum cholesterol, and serum lactic dehydrogenase. The death rate in group A during the year after the albumin analysis was 25%. For the patients with albumin level less than 3.5, 3.5-4.0, and greater than 4.0 g/dl, the death rates were 50%, 43%, and 11% respectively (p less than 0.01 for comparison of the former two groups with the latter). The subgroup with albumin 3.5-4.0 g/dl represented only 37% of the men in group A, but accounted for 63% of the group's deaths. In group B, serum albumin level was not significantly correlated with any other clinical variable. Death rate during the year after the albumin analysis was only 2% in group B, and did not correlate with the albumin level. These data indicate that, in nonpsychiatric Nursing Home men, the desirable level for the serum albumin concentration is higher than 3.5 g/dl.

Adult↗
PubMedDate not supplied

Prognostic significance of serum cholesterol in nursing home men.

Serum cholesterol was measured in 129 men (average age 70.6; range 41-96) of a Veterans Administration Nursing Home, and was correlated with other items in an extensive clinical data base. Serum cholesterol was less than 150 mg/dl in 13% of the subjects, and was less than 160 mg/dl in 18%. Cholesterol greater than 280 mg/dl occurred in 8%. Serum cholesterol varied directly (p less than 0.02) with: body weight, serum albumin, serum total protein, serum sodium, ability to walk, and ability to feed oneself; and indirectly (p less than 0.02) with death rate, degree of functional dependence, and serum SGOT and LDH. Nursing home men with cholesterol less than 150 mg/dl had a death rate of 63% during the 14 months after the cholesterol analysis, compared to a death rate of 9% in men with cholesterol greater than 150 mg/dl (p less than 0.05). Death rate during the year after the analysis was 52% if cholesterol was below 160 mg/dl, compared to 7% if it was above this threshold (p less than 0.05).

Adult↗
PubMedDate not supplied

Dose-responsive characteristics of meperidine sedation in preschool children.

Using double-blind conditions, 60 uncooperative and fearful preschool children (24-66 months) received intramuscular injections of meperidine 0.25, 0.50, 1.00 mg/lb or placebo prior to restorative dental treatment. Behavior was assessed by the dentist and an independent observer during five specific treatment procedures. Behavioral ratings found meperidine to be an effective sedative, with 0.50 mg/lb and 1.00 mg/lb being significantly more effective than placebo (P less than 0.05, Kruskal-Wallis). Children receiving 1.0 mg/lb of meperidine had significantly more nausea and vomiting than patients receiving lower doses of the drug (P less than 0.05, Chisquare). Physiologic monitoring demonstrated that the highest dose of meperidine was associated with transient drops in arterial oxygen saturation. Meperidine sedation was found to be more effective for older children (37-66 months) and for children initially rated as being only moderately uncooperative and fearful.

Anxiety↗
PubMedDate not supplied

Efficacy of a prebrushing rinse for orthodontic patients.

The oral health benefits of a prebrushing rinse, when used in conjunction with an established twice-a-day brushing regimen, was investigated in a population of orthodontic patients. Twenty children (ages 11-18) who were undergoing orthodontic treatment that required brackets and labial wires were enrolled. This randomized, double-blind, cross-over clinical trial compared five weeks of twice-daily use of a commercial prebrushing rinse (Plax) to five weeks of a placebo rinse. Three investigators rated plaque accumulation (Simplified Oral Hygiene Index) and gingival health (modified O'Leary Index) prior to treatment and after each five week session. Because one child exited from the project and three children did not satisfactorily comply with the treatment protocol, sixteen children were used for the analysis. Although both treatment groups showed plaque and gingival improvement from pretreatment scores, no differences in plaque accumulation ratings and gingival health ratings were noted between the active and placebo rinse treatments.

Adolescent↗