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Biomedical subjects

C Jackson

Publications and source records attributed to C Jackson.

At least 235 records · Page 13Linked to original sources
PubMed1988

Studies in gnotobiotic piglets on non-O157:H7 Escherichia coli serotypes isolated from patients with hemorrhagic colitis.

A number of verotoxin-producing Escherichia coli strains isolated from sporadic cases of hemorrhagic colitis in the United States over the last 5 yr were shown to belong to serogroups other than O157:H7-the serotype originally implicated in this disease. Experimental infection of gnotobiotic piglets with five such strains (0111:NM, 0145:NM, 045:H2, 04:NM, and Ound:NM) caused diarrhea resulting from mucosal lesions in the cecum and colon that were indistinguishable from those previously described in piglets infected with E. coli O157:H7. This suggests that, as with other categories of pathogenic E. coli, several serotypes cause hemorrhagic colitis in humans. The five E. coli strains that were compared with one O157:H7 strain and with an enteropathogenic calf strain (serotype 05:NM) caused a spectrum of disease ranging from moderate diarrhea (O157:H7) to severe illness (including septicemia and death) (0111:NM). Characteristic lesions, which were identical for all seven pathogenic strains, included bacterial attachment, effacement of the microvillus border, and dissolution of the cell membranes of surface and glandular epithelium, resulting in complete cell destruction. Some piglets exhibited neurologic signs of convulsions and ataxia. It is concluded that a number of E. coli serotypes, in addition to O157:H7, fulfill the present limited criteria for enterohemorrhagic E. coli, which include association with hemorrhagic colitis, production of one or more verotoxins, possession of a large plasmid (50-70 megadaltons), and induction of distinct mucosal lesions in the large bowel of gnotobiotic piglets.

Animals↗
PubMed1988

Nitrogen metabolism by lactating ewes and their lambs.

Twenty multiparous ewes and their newborn lambs were assigned to a 2 x 2 factorial experiment in which ewes were fed ad libitum either a moderate (MP, 15%) or a low (LP, 10%) CP diet and nursed either twin (T) or single (S) lambs. Nitrogen (N) balance trials were conducted on both the ewes and lambs during wk 2, 4 and 8 of lactation. Nitrogen balance, N digested and the portion of digested N retained were greater (P less than .01) with the MP diet. Nitrogen retention and serum urea-N values were lower for the ewes nursing T lambs. Plasma beta-hydroxybutyrate and serum glucose values were lower (P less than .01) for ewes fed the LP diet, and certain plasma amino acids and the ketogenic amino acids were lower with the LP diet. Insulin increased (P less than .01) with time throughout lactation. Triiodothyronine (T3) concentrations were higher (P less than .01) in ewes nursing T lambs. Thyroxine (T4) was greater (P less than .04) with the LP diet and greater (P less than .01) for ewes nursing T lambs. The T4:T3 ratio was lower (P less than .02) in the ewes consuming LP. The portion of the ewe's retained N used for milk synthesis was lower (P less than .01) with the MP diet. Ewes fed LP and nursing T lambs utilized all of their retained N plus a portion of their body protein reserves for milk production by the 2nd wk of lactation. Body weights of creep-fed lambs were not changed by protein content of the ewe's diet.

Animals↗
PubMed1988

Now hear this.

Explore the source record for details and available documents.

Aged↗
PubMed1987

Comparison of the Matthews Youth Test for Health and the Hunter-Wolf A-B Rating Scale: measures of type A behavior in children.

This study evaluated the extent to which two youth measures of Type A behavior--the Matthews Youth Test for Health (MYTH) and the Hunter-Wolf A-B Rating Scale--similarly assess the Type A construct. Data from 25 elementary teachers and from 300 of their students revealed that these scales are weakly correlated and that the concordance of their Type A-Type B classifications was only slightly above that expected by chance. Weak agreement was found even when teachers and students rated the same Type A behaviors, which suggests that variability in content was not the principal reason for the lack of agreement between these measures. The major implication of this study is that the MYTH and the Hunter-Wolf scale should not be considered interchangeable measures of Type A behavior. The study reveals that investigators' choice of a Type A measure may strongly affect the nature of their research findings and may inhibit the integration of their data with data from other investigators who employ different measures of the Type A construct. It is recommended that, if multiple measures cannot be used in a study, the investigator employ the MYTH.

Child↗
PubMed1987

Syntactic preservation in Alzheimer's disease.

Language ability of 20 patients with probable Alzheimer's disease (AD) was evaluated. Analysis of spontaneous speech revealed a normal range and frequency of syntactic constructions but poor lexical use. A writing task showed a similar divergence, with the ability to use syntactic cues significantly more intact than the ability to use semantic cues. The results are taken to indicate that syntactic ability is selectively preserved in AD. These findings are consistent with a modular theory of grammar and of mental functions more generally. A tentative explanation of these phenomena is proposed in which the overlearned and automatic nature of syntactic ability helps account for its resilience to cognitive dissolution and cortical degeneration.

Aged↗
PubMed1986

Alloviroidin, the naturally occurring toxic isomer of the cyclopeptide viroidin.

A novel toxic cyclopeptide from Amanita suballiacea (Murr.) mushrooms that possesses structural features similar to viroidin is described. This peptide, alloviroidin, is identical with viroidin in mass, affinity for actin, and all amino acids except for one. The single discernible difference between the two peptides exists in the configuration at carbon 4 of the 4,5-dihydroxyleucine residues, as shown by a combination of chemical modification and magnetic resonance experiments. The configuration of this residue in viroidin is similar to that of phalloidin and is 2S,4R, while that in alloviroidin is established to be 2S,4S. This peptide is thus unique in its hydroxylation pattern among both the virotoxins and phallotoxins and may be an intermediate for more highly hydroxylated virotoxins, such as viroisin.

Actins↗
PubMed1986

A controlled study of transitional day care for non-chronically-ill patients.

The authors randomly assigned 79 inpatients with nonchronic schizophrenia or affective disorder to either an intensive experimental day program called "transitional treatment" or a control treatment--weekly clinically believed to require intensive posthospital treatment to make the transition to the community. Although initially there was a significantly higher dropout rate from the control condition, at the point of discharge from the two programs as well as at 6- and 12-month follow-up there was no difference in outcome. Direct costs for the transitional treatment, however, were much higher.

Adolescent↗
PubMed1986

Left hemisphere intracerebral hemorrhages studied by ( (F-18)-fluorodeoxyglucose PET.

We used PET to study patients with intracerebral hemorrhages in the left hemisphere. Three anatomic and physiologic patterns were observed. Patients 1 and 2 had midputamen hemorrhages with diffuse left less than right hemispheric metabolic asymmetry most prominent in temporal and parietal regions. Patients 3 and 4 had posterior putamen-insula-temporal hemorrhages with left less than right metabolic asymmetry in temporoparietal cortex and thalamus. Patients 5, 6, and 7 had smaller posterior hemorrhages. Left cortical metabolism was little affected in these three cases. Persistent aphasia was associated with severe metabolic left less than right asymmetry in posterior middle temporal regions.

Adult↗
PubMed1985

The nurse as a survivor: delayed post-traumatic stress reaction and cumulative trauma in nursing.

As opposed to studies on the immediate psychological impact of traumatic nursing experiences, little attention has been directed to the persistence of certain long-standing hidden symptoms of trauma in some nurses. Since psychological reactions to trauma are claimed to be similar, irrespective of the source of trauma, it is postulated that findings from recent studies on delayed post-traumatic stress reaction in Vietnam veterans, victims of natural disaster, and survivors of the holocaust, delineate symptoms which are also found in stress-prone nurses utilizing maladaptive coping strategies in response to hospital-related traumatic episodes. While some observations are conjectural and speculative, an integrated review is presented of areas of research hitherto unrelated, which serves to deepen our understanding of trauma and its impact upon the mental health of nurses.

Adaptation, Psychological↗
PubMed1985

Factors that affect the HMO enrollment decision: a tale of two cities.

Although there is agreement that utilization patterns in HMOs differ from those in non-HMO systems, there is less agreement on how and why these differences are achieved. Selection bias is one frequently offered explanation. In an attempt to identify those individual and site-specific factors that help determine employees' choice of coverage, we developed and tested a logistic model of the enrollment decision. We used both survey data and claims data to study the decision to enroll in either an HMO or a traditional indemnity plan among state employees in Tallahassee, Florida, and Salt Lake City, Utah. We found that many factors affected the decision--factors that could be altered by an HMO or insurance company to correct selection bias if and when it is encountered.

Adult↗
PubMed1985

Serum amino acids as indicators of protein status in gestating ewes.

Changes in the serum amino acids of ewes obtained with regulated protein intakes may be of value for indicating the status of protein metabolism during gestation. Thirty crossbred ewes in midgestation were assigned in equal numbers to three treatments of 12%, 9% and 7% crude protein, isocaloric diets fed al libitum. Serum amino acids were determined by reverse phase, high performance liquid chromatography. Several consistent amino acid changes were related to protein intake over the last half of gestation. Glutamine plus alanine were increased and the branched chain amino acids (isoleucine, valine and leucine) were reduced. These responses suggest that tissues, such as muscle, undergo catabolism during late gestation as a result of low protein intake to release glutamine and alanine for gluconeogenesis. Serum Leu was reduced by a decreased level of dietary protein indicating inadequate protein status. Lowering protein intake also induced a consistent increase in serine through the last half of gestation. Increasing serine values may be the result of induced synthesis by liver in response to the low protein intake. This possibility suggests that the protein status of gestating ewes can be evaluated by following serum amino acid changes and the release of amino acids from specific tissues such as liver and muscle can be monitored through changes in the circulating amino acid values.

Amino Acids↗
PubMed1984

Brain mitochondrial metabolism in experimental thiamine deficiency.

Thiamine deficiency causes Wernicke's encephalopathy, although the precise mechanism is unknown. We used a low-thiamine diet in conjunction with a thiamine analog, pyrithiamine, as a model of severe thiamine deficiency in rats. We investigated the function of intact, coupled mitochondria isolated from both brain and liver. State 4 respiration did not change in the thiamine-deficient animals. Brain state 3 rates fell in thiamine-deficient animals when pyruvate/malate, alpha-ketoglutarate, or glutamate were used as substrate. Liver state 3 rates were depressed only when pyruvate/malate was substrate. Activities of brain and liver pyruvate dehydrogenase complex and alpha-ketoglutarate dehydrogenase complex were depressed in the thiamine-deficient group. We conclude that the mitochondrial abnormalities resulting from thiamine deficiency are secondary to depression of thiamine-mediated enzyme activity, rather than from a putative role of thiamine in chemiosmotic coupling, and that the resulting abnormalities in ATP synthesis and perhaps in glutamate catabolism result in the irreversible neurologic defect seen in this disease.

Animals↗