PubMed Health⌕ Search

Biomedical subjects

N Prentice

Publications and source records attributed to N Prentice.

At least 19 recordsLinked to original sources
PubMed2006

Detection of Enterobacter sakazakii in dried infant milk formula by cationic-magnetic-bead capture.

Enterobacter sakazakii has been associated with life-threatening infections in premature low-birth-weight infants. Contaminated infant milk formula (IMF) has been implicated in cases of E. sakazakii meningitis. Quick and sensitive methods to detect low-level contamination sporadically present in IMF preparations would positively contribute towards risk reduction across the infant formula food chain. Here we report on the development of a simple method, combining charged separation and growth on selective agar, to detect E. sakazakii in IMF. This protocol can reliably detect 1 to 5 CFU of E. sakazakii in 500 g of IMF in less than 24 h.

Bacteriological Techniques↗
PubMed2002

Gap junction proteins and cell-cell communication in the three functional zones of the adrenal gland.

Mouse and monkey adrenal glands were used to study the relationships between gap junction protein expression, intercellular communication and adrenal zonation. Dye communication patterns were determined by incubating freshly excised and hemisected adrenal glands in Lucifer yellow, a gap junction permeable fluorescent dye. Immunohistochemical techniques were used to localize adrenal gap junction proteins. The combination of these two techniques permitted the correlation of gap junction proteins with dye transfer and hormone responses in specialized regions of the adrenal cortex. Lucifer yellow dye communication was most pronounced in the inner glucocorticoid/androgen-producing regions (zona fasciculata/zona reticularis), but was virtually absent in the outer mainly mineralocorticoid-producing region (zona glomerulosa). This pattern of dye communication was coincident with immunohistochemical localization of the gap junction protein, alpha(1)Cx43. The variations in communication and alpha(1)Cx43 expression within the adrenal cortex are thought to be relevant to normal physiological regulation of the adrenal gland.

Adrenal Cortex↗
PubMed2000

HIV+ patients have increased lymphocyte infiltrates in CIN lesions.

OBJECTIVE: The objective of our study was to analyze immunocyte infiltrates in CIN lesions from HIV+ patients to assess whether local immunosuppression, defined as a decrease in T cell infiltrates, could explain the aggressive nature of CIN in HIV-infected patients. MATERIALS AND METHODS: Cervical tissue was obtained from 6 HIV+ CIN patients, 6 HIV- CIN patients, who underwent LLETZ (large loop excision of the transformation zone) for CIN, and 17 normal patients who underwent hysterectomy for benign indications. The following cell surface markers were analyzed: CD20 (B cells), CD4 (T helper cells), and CD8 (T suppressor/cytotoxic cells). Each tissue section was visualized with a Leica microscope at 400x and the image was captured for analysis by Harmony Group image analysis software. RESULTS: A significantly higher number of lymphocytes (both B and T cells) was detected in the stroma of HIV+/CIN tissue compared to either HIV-/CIN or normal tissue. There was also a significant increase in CD8+ cells in the HIV+/CIN group compared to HIV-/CIN or normal tissue. There was a trend toward a decreased CD4+/CD8+ ratio in the HIV+/CIN compared to the other two groups; however, this did not reach statistical significance. CONCLUSIONS: This study indicates that HIV+/CIN cervical tissue has a greater number of tissue lymphocytes recruited to the neoplastic site compared to HIV- individuals. In addition, HIV+ patients may have a decreased CD4/CD8 ratio in locally infiltrating immunocytes in CIN lesions. The local immunomodulatory effects of HIV may be detectable early in infection and therefore may explain the aggressive nature of CIN in the HIV+ patient.

CD4-CD8 Ratio↗
PubMed1999

Follow-up study of depression in the elderly. Clinical and SPECT data.

BACKGROUND: Imaging studies in depression of the elderly are often small and highly selective. AIMS: To investigate a large group of elderly depressed patients in order to assess changes in clinical, imaging and neuropsychological variables at follow-up. METHOD: Patients (n = 175, age range 65-91 years) with clinical depression were identified from consecutive local referrals. Clinical interviews, neuropsychological tests and SPECT scans were carried out at referral and at two-year follow-up. RESULTS: Of 84 re-examined patients, 46.5% were well, 9.5% were ill, 33% partially recovered and 11% had developed dementia. Duration of illness before index assessment was the only factor to predict outcome. Thirty-nine patients could be scanned and followed up. There were no differences between patients with good or poor depressive outcome on SPECT. Ten clinically improved patients could be re-examined with SPECT. There were relative increases in right cingulate gyrus and right cerebellum at follow-up. CONCLUSIONS: The patients group was comparable with other studies showing high levels of residual depressive symptoms. Activity changes in limbic cortex are implicated in depression of old age.

Aged↗
PubMed1998

A voxel-based analysis of cerebral perfusion in dementia and depression of old age.

Thirty-nine elderly depressed patients as well as 15 demented patients with Alzheimer's disease and 11 healthy volunteers were imaged at rest with a high resolution single-slice 12-detector head scanner (SME-Neuro 900) and the cerebral perfusion marker 99mTc-Exametazime (HM-PAO). Statistical parametric maps were computed to compare early- and late-onset depressed, Alzheimer patients and healthy volunteers and to examine associations between regional perfusion and clinical and MRI variables. Patients with late-onset depression showed reductions in temporal lobe perfusion compared with early-onset depression and controls. Alzheimer patients had the expected reduced perfusion in temporoparietal and prefontal cortex, as well as basal ganglia, compared with healthy controls. Compared with depressed patients, they showed a relative reduction in temporoparietal cortex, only. This difference was more pronounced between Alzheimer patients and early onset, compared to late-onset patients with depression. Periventricular white matter changes on MRI were associated with temporal lobe reductions of tracer uptake in depression. In the Alzheimer group, deep white matter MRI changes were associated with frontal perfusion deficits. Our results support a vulnerability hypothesis, which predicts that patients with late-onset depression will show more brain changes than patients with an early onset of their illness. Statistical parametric mapping in patients with organic psychiatric brain syndromes is feasible and promising as a clinical and research method.

Aged↗
PubMed1997

Performance on the delayed word recall test (DWR) fails to differentiate clearly between depression and Alzheimer's disease in the elderly.

BACKGROUND: The differential diagnosis of early dementia of the Alzheimer's type from depression in the elderly is often made difficult by the presence of significant memory impairment in depressed patients. The Delayed Word Recall test (DWR) was developed to facilitate the early diagnosis of Alzheimer's disease. The DWR involves: (a) repeated elaborate encoding of ten separate words; (b) a filled delay; (c) delayed free recall. A recognition memory test has also been recently developed. The available evidence suggests impressive sensitivity and specificity when the DWR has been used to separate patients with early Alzheimer's disease from very well matched controls. METHODS: In the present study, the DWR was evaluated with regard to its ability to separate a group of 50 patients with early Alzheimer's disease from 50 elderly patients with major depression in a between-subjects experimental design. RESULTS: For both free recall and recognition indices, the between-group overlap was large. Using recommended cut-off scores for the detection of Alzheimer's disease, 44% of the depressed patients would have been misclassified as demented based on their free recall scores, and 48% of the depressed patients would have been misclassified on the basis of their recognition scores. CONCLUSION: We conclude that the DWR is not specific enough to clearly distinguish patients with early Alzheimer's disease from elderly patients with major depression.

Aged↗
PubMed1997

Temporal lobe abnormalities in dementia and depression: a study using high resolution single photon emission tomography and magnetic resonance imaging.

OBJECTIVES: Perfusion SPECT and MRI were used to test the hypothesis that late onset depression is associated with brain abnormalities. METHODS: Forty depressed patients (DSM-III-R major depressive episode, not demented at two year follow up) were recruited who were either drug free, or on a stable dose of antidepressants for at least three weeks, as well as 22 demented patients (DSM-IIIR and NINCDS/ADRDA criteria for probable Alzheimer's disease). Patients were imaged at rest with a high resolution single slice 12 detector head scanner (SME-Neuro 900) and the cerebral perfusion marker 99mTc-exametazime (HM-PAO). Temporal lobe templates were fitted with brains pitched by 20 degrees-30 degrees. A subgroup of 41 patients (22 depressed) were also scanned using a Siemens Magnetron 1.0 Tesla magnetic resonance imager, using a FLAIR imaging sequence for the assessment of white matter hyperintensities, and a Turbo FLASH sequence for the measurement of medial temporal lobe width. RESULTS: Demented patients showed reduced perfusion, particularly in the left temporoparietal cortex. In these regions of interest, patients with late onset depression tended to have perfusion values intermediate between patients with early onset depression and demented patients. Differences in changes in white matter between demented and early and late onset depressive patients did not reach conventional levels of significance. Temporal lobe width differed between demented and depressed patients, but not between early and late onset depressed patients. Perfusion and temporal lobe width were not associated, but reductions of perfusion were associated with periventricular white matter changes. Mini mental state examination scores were associated with temporal perfusion in demented patients and with changes in deep white matter in depressed patients. Finally, severity of depressive symptoms was associated with decreased perfusion in frontotemporal and basal ganglia regions of interest. CONCLUSION: A cumulative effect of duration of illness on regional cerebral perfusion could not be confirmed. Late onset depression may show more abnormalities of deep white matter and of left temporoparietal perfusion than early onset depression, but the underlying pathology remains to be established.

Aged↗
PubMed1995

Further evidence that reading ability is not preserved in Alzheimer's disease.

BACKGROUND: Pre-morbid intelligence level is routinely assessed in Alzheimer's disease using the National Adult Reading Test (NART). This practice is based on the assumption that pronunciation of irregular words remains unaffected by the disease process. Recent reports have suggested that reading ability may become compromised in moderately demented subjects. METHOD: Sixty-eight probably Alzheimer patients were classified into stages of severity (minimal, mild and moderate) using the Mini-Mental State Examination (MMSE). NART and demographic equations were used to estimate pre-morbid ability. RESULTS: A significant correlation emerged between dementia severity and reading ability, NART v. MMSE scores, r = 0.46, P < 0.01. When the total sample was subdivided into moderate, mild and minimal subgroups, significant between-group differences emerged, despite the groups being well matched for age, sex, and years of full-time education. Pre-morbid IQ, as estimated by demographic regression equations, did not correlate with dementia severity. CONCLUSION: NART performance is compromised in moderate Alzheimer disease, and the measure provides a serious underestimate of pre-morbid IQ in patients with an MMSE of 13 or less.

Aged↗
PubMed1994

Uptake of 99mTc-exametazime shown by single photon emission computerized tomography in obsessive-compulsive disorder compared with major depression and normal controls.

Twelve patients with obsessive-compulsive disorder (OCD) were investigated at rest using single photon emission computerized tomography with 99mTc-exametazime. The uptake of 99mTc-exametazime was expressed relative to calcarine/occipital cortex. Patients were matched for drug treatment with 12 patients with a major depressive episode and the patient groups were compared with a control group. Significant bilateral decreases in tracer uptake were confined to basal ganglia in the OCD group. There was a paradoxical positive correlation between anxiety ratings and tracer uptake to basal ganglia in the OCD group. The findings confirm that the functional topography of OCD implicates altered function in the basal ganglia.

Adult↗
PubMed1993

State changes in brain activity shown by the uptake of 99mTc-exametazime with single photon emission tomography in major depression before and after treatment.

Twenty-eight patients with a major depressive episode previously investigated at rest using Single Photon Emission Tomography (SPET or SPECT) with 99mTc-exametazime, were followed up at an interval of 9-28 months with the same investigation after full recovery. All patients were unipolar and were rated on the Newcastle scale and with the 17-item Hamilton scale. The uptake of 99mTc-Exametazime was expressed relative to calcarine/occipital cortex. Sixteen patients were scanned when optimally matched for drug treatment (4) or on both occasions drug free (12). The other 12 patients were fully recovered but could not be matched for drug status; these patients showed significantly more retardation, diurnal mood variation and guilt at presentation. Significant bilateral increases in tracer uptake were confined to basal ganglia and inferior anterior cingulate cortex in the matched group, where there were additional increases in thalamus and posterior cingulate cortex on the right side. There were no statistically discernible changes in the neocortex in the matched sample. The unmatched sample yielded inconclusive evidence of increased tracer uptake in left temporal cortex. The findings give a potential focus to the neuropharmacological analysis of depressive illness because the topography of the state change in brain function implicates dopamine function.

Adult↗
PubMed1993

The elevation of plasma beta-endorphin levels in major depression.

Day-time plasma beta-endorphin/beta-lipotrophic hormone (beta-ENDO/beta-LPH), ACTH and cortisol have been determined in 26 patients with major depression and 25 controls. beta-ENDO/beta-LPH and cortisol were significantly elevated in patients, while ACTH was not. Cortisol levels were significantly negatively correlated with age in controls as were beta-ENDO/beta-LPH and ACTH. In patients, by contrast, cortisol levels were positively, albeit not significantly, related to age. Peptide levels were not related to age in the patient group. Instead, beta-ENDO/beta-LPH was negatively correlated with clinical ratings of symptom severity in patients and positively associated with an acute psychosocial precipitant. The findings cast further light on beta-ENDO/beta-LPH as a measure of hypothalamic-pituitary over activity in depressive illness. A negative association with symptom severity suggests that beta-ENDO/beta-LPH responses are, like those of ACTH, down-regulated in the course of depressive illness.

Adrenocorticotropic Hormone↗
PubMed1984

Influence of culture filtrate of Trichoderma viride and barley on lipid metabolism of laying hens.

The suppression of hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase and cholesterol 7 alpha-hydroxylase, previously noted in studies of the influences of barley and the filtrate of Trichoderma viride culture (CF) on cholesterol metabolism in sexually immature birds, is shown in sexually mature birds. Barley, CF or both were fed in one study from the day of hatching, in another during the period of sexual maturation and, in a third study, CF was fed to mature layers. CF suppressed HMG CoA reductase by 30-50% and cholesterol 7 alpha-hydroxylase by 32-45% when added to the control diet. In birds fed barley rather than corn, the respective activities were 25-36% and 24-31% lower. These effects were expressed in the lowering of plasma cholesterol by 11-36%. Lipogenic activity based on the assays of 4 enzymes was increased 2-3 times by the treatments and plasma triglyceride elevated by 12-86%. The start of egg production by birds fed CF preceded the controls by 17 days. Birds fed barley trailed controls by 11-14 days. CF countered the barley-conditioned delay. Egg yolk cholesterol concentrations were lowered by both treatments. Eggs produced by hens fed barley were lower in weight; CF increased egg and yolk weights. Tissues from birds fed CF or barley for up to 30 weeks appeared to be normal.

Animal Feed↗
PubMed1982

Effects of different fractions of the barley kernel on the hepatic lipid metabolism of chickens.

Various physical fractions of the barley kernel were fed to one-day-old female and male chickens to determine their effect on hepatic beta-hydroxy-beta-methylglutaryl coenzyme A (HMG-CoA) reductase, cholesterol 7 alpha-hydroxylase and the lipogenic enzymes, acetyl-CoA carboxylase (ACX), malic enzyme (ME), citrate-cleavage enzyme (CCE) and fatty acid synthetase (FAS) at the subcellular level. Significant inhibition (p less than 0.01) of cholesterol biosynthesis accompanied by significant decreases in plasma cholesterol concentrations and induction of fatty acid synthesis were found in diets based on pearled barley, barley pearlings and a high-protein barley flour (HPBF: aleurone and subaleurone layers of barley endosperm) separated from the pearlings when compared to corn. Lower weight gains in 1- to 4-week-old birds fed the high-protein barley flour were found to be the result of lower feed consumption; pair feeding of 12-week-old birds with diets based on corn and high-protein barley flour produced equal weight gains in both treatments and significant reductions in hepatic HMG-CoA reductase, plasma cholesterol and induction in several lipogenic enzymes in birds fed the high-protein barley flour. Substitutions of 5-20% high-protein barley flour for corn in a corn-based diet produced significant weight gains (p less than 0.01) of 10 to 20% in 2-week-old chickens, inhibited cholesterol biosynthesis by 45-65% and produced a 3-fold increase in a fatty acid synthetase. The results indicate that HPBF contains an inhibitor(s) of cholesterol biosynthesis and a growth factor(s) when compared to a corn-based diet.

Animals↗
PubMed1981

The viscosity interaction of barley beta-glucan with Trichoderma viride cellulase in the chick intestine.

A culture filtrate from Trichoderma viride was used as a source of cellulose degrading enzymes. This filtrate, when added to a barley ration fed to chicks, improved growth and feed efficiency by 19% and 8%, respectively. The response was saturable since increasing amounts of filtrate above 50 mg/kg produced no further improvement. Barley eta-glucan was added to a corn-based diet (10 g/kg) to evaluate the effect of the culture filtrate on the viscosity of beta-glucan in the chick intestinal contents. Barley beta-glucan increased the viscosity of the supernatant of the chick intestinal contents threefold and the culture filtrate reduced the viscosity to near control levels when combined with the diet containing beta-glucan. The presence of beta-glucan in barley probably limits growth of chicks by increasing viscosity of intestinal contents.

Animals↗
PubMed1980

Regulation of lipid metabolism in chicken liver by dietary cereals.

The activities of acetyl-CoA carboxylase (EC 6.4.1.2), fatty acid synthetase (FAS) and beta-hydroxy-beta-methylglutaryl-CoA (HMG-CoA) reductase (EC 1.1.1.88) were determined in subcellular fractions of livers from chicks fed different cereal-based diets. With a barley-based diet as compared to corn, the following was observed: body and liver weights decreased 31%; HMG-CoA reductase activity of liver decreased 79%; acetyl-CoA carboxylase activity increased 3-fold; fatty acid synthesis increased 5-fold, and plasma and liver cholesterol decreased 45% and 35%, respectively. The suppression and induction of activities of the two divergent pathways (cholesterol and fatty acid biosynthesis) persisted for at least 21 days. Wheat, oats and rye showed a similar but less pronounced effect. The pronounced decrease in plasma cholesterol level and HMG-CoA reductase activity have implications for human nutrition and possible control of the cardiovascular diseases in which cholesterol plays a key role.

Acetyl-CoA Carboxylase↗
PubMed1975

Stability of aflatoxin B-1 and ochratoxin A in brewing.

The stability of aflatoxin B-1 and ochratoxin A in brewing was investigated by adding the purified toxins to the raw materials at 1 and 10 mug/g levels during mashing in a conventional micro-brewing process. The results indicate that both toxins are stable to heat and are insensitive to cooker mash treatment. Both mycotoxins were partially removed in the mashing and brewing processes. About 14 to 18% and 27 to 28% of the added toxins were found in the final beers brewed from starting materials containing 1 and 10 mug, respectively, of either toxin per g. The possible route of transmission of mycotoxins into beer is discussed.

Aflatoxins↗