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Biomedical subjects

M L Jackson

Publications and source records attributed to M L Jackson.

At least 19 recordsLinked to original sources

Contrast sensitivity and visual hallucinations in patients referred to a low vision rehabilitation clinic.

AIM: To examine the association of reported visual hallucinations and measured visual parameters in adult patients referred for low vision rehabilitation. METHODS: All patients (N = 225) referred to a low vision rehabilitation clinic for a calendar year were asked a standardised question about symptoms of formed visual hallucinations. Best corrected visual acuity and contrast sensitivity using the Pelli-Robson chart were measured. We conducted multiple logistic regression analysis of the association between visual hallucinations and visual parameters. RESULTS: Of the total cohort, 78 (35%) reported visual hallucinations. Visual acuity and contrast sensitivity were considered in four quartiles. In multiple logistic regression controlling for contrast sensitivity, age, gender, report of depression and independence, measured acuity in each of the poorer three categories (compared to the best) was not associated with reported hallucinations. Contrast sensitivity in the three poorer quartiles (compared to the best) was strongly associated with the report of hallucinations (OR 4.1, CI 1.1, 15.9; OR 10.5, CI 2.6, 42.1; OR 28.1, CI 5.6, 140.9) after controlling for acuity, age, sex, depression and independence. CONCLUSIONS: Lowest contrast sensitivity was the strongest predictor of reported hallucinations after adjusting for visual acuity.

Aged↗

Immunohistochemical and histochemical stains for differentiating canine cutaneous round cell tumors.

Immunohistochemical and histochemical stains are useful adjunct techniques in the diagnosis of canine cutaneous round cell tumors, which can appear histologically similar. We applied a panel of monoclonal antibodies (recognizing tryptase, chymase, serotonin for mast cells; CD1a, CD18, MHC class II for histiocytes; CD3 for T lymphocytes; CD79a for B lymphocytes and plasma cells) and one histochemical stain (naphthol AS-D chloroacetate for chymase activity) to formalin-fixed, paraffin-embedded sections of canine cutaneous mast cell tumors, histiocytomas, lymphosarcomas, plasmacytomas, and unidentified round cell tumors. Of 21 tumors with a histologic diagnosis of mast cell tumor, 7/7 (100%) grade I, 6/7 (85.7%) grade II, and 3/7 (42.9%) grade III tumors were diagnosed as mast cell tumors based on positive staining for tryptase antigen and chymase activity. Mast cells were positive for both tryptase antigen and chymase activity, indicating equal efficacy of tryptase immunohistochemistry and chymase histochemistry. Chymase was detected immunohistochemically in both tumor and nontumor cells, while serotonin was not detected in most mast cell tumors, and thus, neither was useful in the diagnosis of mast cell tumors. Immunohistochemistry to detect CD18 and MHC class II was equally effective in staining histiocytomas, although lymphosarcoma must be ruled out through the use of CD3 and CD79a immunohistochemistry. Immunohistochemistry using three different monoclonal antibodies to human CD1a showed no cross-reactivity in canine histiocytomas and was not useful. A final diagnosis was obtained for 4/5 (80%) of the unidentified tumors, indicating the usefulness of multiple stains in poorly differentiated round cell tumors.

Animals↗

Self-help and long-term behavior therapy for obesity.

The Trevose Behavior Modification Program, a self-help group offering continuing care for obesity, has recently been shown to produce large long-term weight losses. The present study aimed to replicate this finding across different settings and participants, assessing the weight losses and attrition rates of 128 participants in three Trevose program satellite groups that used the same treatment procedures and manual as the central Trevose group. The satellite groups' results closely paralleled those of the Central Group. Mean intent-to-treat weight loss, or final losses recorded for all participants regardless of their treatment termination date, was 13.7 +/- 0.7% of initial body weight (1.8 +/- 0.7 kg). At two years, 43.8% of participants remained in treatment, having lost a mean of 19.0 +/- 0.8% of their body weight (16.2 +/- 1.0 kg); at five years, 23.4% remained, having lost 18.4 +/- 1.1% of body weight (15.6 +/- 1.5 kg). These results demonstrate that the Trevose model of weight control, combining self-help and continuing care, can be extended and disseminated to other settings, with potentially significant public health consequences.

Behavior Therapy↗

Feline leukaemia virus status of Australian cats with lymphosarcoma.

OBJECTIVE: To determine the FeLV status of sera and tumours from Australian cats with lymphosarcoma in relation to patient characteristics, tumour characteristics (tissue involvement, histological grade and immunophenotype), haematological and biochemical values. DESIGN: Prospective study of 107 client-owned cats with naturally-occurring lymphosarcoma. PROCEDURE: An ELISA was used to detect FeLV p27 antigen in serum specimens collected from cats with lymphosarcoma. A PCR was used to detect FeLV DNA in formalin-fixed, paraffin-embedded tissue sections containing neoplastic lymphoid cells. The PCR was designed to amplify a highly conserved region of the untranslated long terminal repeat of FeLV provirus. RESULTS: Only 2 of 107 cats (2%), for which serum samples were available, were FeLV-positive on the basis of detectable p27 antigen in serum. In contrast, 25 of 97 tumours (26%) contained FeLV DNA. Of the 86 cats for which both PCR and ELISA data were available, 19(22%) had FeLV provirus in their tumours but no detectable circulating FeLV antigen in serum, while 2 (2%) had FeLV provirus and circulating FeLV antigen. FeLV PCR-positive/ELISA-negative cats (19) differed from PCR-negative/ELISA-negative cats (65) in having fewer B-cell tumours (P = 0.06), more non B-/non T-cell tumours (P = 0.02) and comprising fewer non-Siamese/Oriental pure-bred cats (P = 0.03). CONCLUSIONS: The prevalence of FeLV antigen or provirus was considerably lower in our cohort of cats compared with studies of lymphosarcoma conducted in the Northern hemisphere. This suggests that factors other than FeLV are important in the development of lymphosarcoma in many Australian cats. No firm conclusions could be drawn concerning whether FeLV provirus contributed to the development of lymphosarcoma in PCR-positive/ELISA-negative cats.

Animals↗

Application of a direct flow cytometric erythrocyte immunofluorescence assay in dogs with immune-mediated hemolytic anemia and comparison to the direct antiglobulin test.

A direct flow cytometric erythrocyte immunofluorescence assay (FC) was developed and compared with the direct antiglobulin test (DAT) for detection of erythrocyte-bound immunoglobulin (IgG and IgM) and complement (C3) in dogs with immune-mediated hemolytic anemia (IMHA). Tests were performed on erythrocytes from 13 healthy nonanemic dogs and from 13 anemic dogs with IMHA. The FC and DAT were negative for erythrocyte-bound immunoglobulin in all healthy dogs. The FC was negative for erythrocyte-bound C3 in 12 healthy dogs and positive in 1 healthy dog, and the DAT was negative for C3 in all healthy dogs. Of the 13 IMHA dogs tested for erythrocyte-bound IgG, 12 were positive using the FC and 7 were positive using the DAT. Sensitivity for the detection of erythrocyte-bound IgG in the 26 dogs was 92% for FC and 53% for DAT. Specificity for detection of erythrocyte bound IgG for FC and DAT was 100%. The addition of IgM and/ or C3 did not increase the sensitivity for FC or DAT. In this group of dogs, the FC provided a more rapid, cost-effective, sensitive, objective method to quantitate erythrocyte-bound immunoglobulin and/or complement compared with the currently used DAT.

Anemia, Hemolytic↗

Immunohistochemical detection of tumor suppressor gene p53 protein in feline injection site-associated sarcomas.

Sarcomas associated with injection sites are a rare but important problem in cats. Immunohistochemical detection of p53 protein may correlate to mutation of the p53 tumor suppressor gene, a gene known to be important in oncogenesis. The expression of nuclear p53 protein in 40 feline injection site-assocated sarcomas was examined by immunohistochemical staining. In 42.5% (17/40), tumor cell nuclei were stained darkly; in 20% (8/40), tumor cell nuclei were stained palely; and in 37.5% (15/40), tumor cell nuclei were unstained. Immunohistochemical detection of p53 protein in a proportion of injection site-associated sarcomas suggests that mutation of the p53 gene may play a role in the pathogenesis of these tumors.

Animals↗

Comparative examination of cats with feline leukemia virus-associated enteritis and other relevant forms of feline enteritis.

Cats with feline leukemia virus (FeLV)-associated enteritis (FAE), enteritis of other known viral etiology (parvovirus [PV], enteric coronavirus [CoV]), and enteritis of unknown etiology with histologic features similar to those of FAE and PV enteritis (EUE) and FeLV-negative and FeLV-positive cats without enterocyte alterations were examined. Amount and types of infiltrating leukocytes in the jejunum and activity and cellular constituents of mesenteric lymph nodes, spleen, and bone marrow were determined. PV and CoV infections were confirmed by immunohistologic demonstration of PV and CoV antigen, ultrastructural demonstration of viral particles in the intestinal content, and in situ hybridization for PV genome. FeLV infection was detected by immunohistology for gp70, p27, and p15E. Latent FeLV infection was excluded by polymerase chain reaction methods for exogenous FeLV DNA. Enterocyte lesions involved the crypts in cats with PV enteritis, FAE, and EUE and the villous tips in cats with CoV enteritis. Inflammatory infiltration was generally dominated by mononuclear cells and was moderate in the unaltered intestine and in cats with PV enteritis and marked in cats with FAE, CoV enteritis, and EUE. In cats with EUE, myeloid/histiocyte antigen-positive macrophages were relatively numerous, suggesting recruitment of peripheral blood monocytes. Lymphoid tissues were depleted in cats with PV enteritis and with EUE but were normal or hyperplastic in cats with FAE. Bone marrow activity was decreased in cats with PV enteritis; in cats with FAE or EUE and in FeLV-positive cats without enterocyte alterations, activity was slightly increased. In cats with FAE and PV enteritis, a T-cell-dominated response prevailed. EUE showed some parallels to human inflammatory bowel disease, indicating a potential harmful effect of infiltrating macrophages on the intestinal epithelium.

Animals↗

Comparison of endogenous feline leukemia virus RNA content in feline vaccine and nonvaccine site-associated sarcomas.

OBJECTIVE: To determine whether feline vaccine site-associated sarcomas (VSS) contain a higher amount of endogenous FeLV (enFeLV) RNA, compared with feline nonvaccine site-associated sarcomas (non-VSS). SAMPLE POPULATION: Formalin-fixed paraffin-embedded (FFPE) tissues from 50 VSS and 50 cutaneous non-VSS. PROCEDURE: RNA was extracted from FFPE sections of each tumor, and regions of the long terminal repeat (LTR) and envelope (env) gene of enFeLV were amplified by use of reverse transcriptase-polymerase chain reaction (RT-PCR). The density of each RT-PCR product band for enFeLV was compared with that of a constitutively expressed gene, glyceraldehyde-3-phosphate dehydrogenase (GAPDH). An integrated density value (IDV) was determined by use of densitometry, and the IDV ratio for enFeLV to GAPDH was calculated for each enFeLV primer set. RESULTS: The median (interquartile range) of the IDV ratio for the enFeLV LTR primer set was 0.52 (0.26 to 1.17) for the VSS group and 0.84 (0.21 to 1.53) for the non-VSS group. The median (interquartile range) of the IDV ratio for the enFeLV env primer set was 0.60 (0.37 to 0.91) for the VSS group and 0.59 (0.36 to 1.09) for the non-VSS group. CONCLUSIONS: Because the amount of enFeLV RNA within the LTR and env gene was not significantly different between the VSS and non-VSS groups, enFeLV replication or expression is unlikely to be involved in VSS development.

Animals↗

Evaluation of formalin-fixed paraffin-embedded tissues from vaccine site-associated sarcomas of cats for polyomavirus DNA and antigen.

OBJECTIVE: To determine whether vaccine site-associated sarcomas (VSS) from cats contain polyomavirus antigen or DNA. SAMPLE POPULATION: 50 formalin-fixed paraffin-embedded tissue blocks of VSS from cats. PROCEDURE: Sections from each tissue block were evaluated for polyomavirus antigen by use of an avidin-biotin-complex immunohistochemical staining method, using rabbit anti-murine polyomavirus polyclonal antiserum as the primary antibody. The DNA was extracted from sections of each tissue block, and a polymerase chain reaction assay was performed, using primers designed to amplify regions of the bovine polyomavirus genome and consensus polyomavirus primers designed to detect unknown polyomaviruses. RESULTS: Polyomavirus antigen and DNA were not detected in any of the VSS. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that polyomaviruses likely do not have any direct involvement in the pathogenesis of VSS in cats.

Animals↗

Evaluation of formalin-fixed paraffin-embedded tissues from vaccine site-associated sarcomas of cats for papillomavirus DNA and antigen.

OBJECTIVE: To determine whether vaccine site-associated sarcomas (VSS) from cats contain papillomavirus antigen or DNA. SAMPLE POPULATION: 50 formalin-fixed paraffin-embedded tissue blocks of VSS from cats. PROCEDURE: Sections from each tissue block were evaluated for papillomavirus antigen by use of an avidin-biotin-complex immunohistochemical staining method, using rabbit anti-bovine papillomavirus type-1 antibody. The DNA was extracted from sections of each tissue block, and polymerase chain reaction assays were performed, using primers designed to amplify regions of the E5 gene of bovine papillomavirus and consensus primers designed to amplify a region of the L1 gene of animal papillomaviruses. Sections from 20 of the tissue blocks were evaluated by use of nonradioactive in situ hybridization for bovine papillomavirus DNA. RESULTS: Papillomavirus antigen and DNA were not detected in any of the VSS. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that papillomaviruses likely do not have any direct involvement in the pathogenesis of VSS in cats.

Animals↗

Effective long-term treatment of obesity: a continuing care model.

BACKGROUND: Despite the well-documented success of behavioral techniques in producing temporary weight loss, treatment is typically followed by weight regain. The maintenance of treatment effects may therefore be the greatest challenge in the long-term management of obesity, and continuous care may be necessary to achieve it. OBJECTIVE: To describe the design and evaluate the effectiveness of the Trevose Behavior Modification Program, a potentially widely replicable self-help weight loss program offering continuous care. DESIGN: A description of the course of all subjects (n=171) who entered the Trevose program during 1992 and 1993. SUBJECTS: One hundred and forty-six women aged 44.1+/-11.7 y with a body mass index (BMI, kg/m2) of 33.2+/-4.4, and 25 men aged 49. 0+/-19.6 with a BMI of 35.1+/-5.2 enrolled in the Trevose program during 1992-1993. RESULTS: Mean duration of treatment was 27.1 months, with 47.4% of members still in treatment at 2 y and 21.6% at 5 y. Mean intent-to-treat weight loss was 13.7+/-0.5% of initial weight, or 12.8+/-0.5 kg. As long as they remained in treatment, almost all participants lost at least 5% of their initial weight and at least 83% lost more than 10%. Members completing 2 y of treatment lost an average of 19.3% of their initial body weight (17.9 kg); at 5 y the loss was still 17.3% (15.7 kg). After leaving the program, subjects regained weight but remained 4.7% (4.5 kg) below their pretreatment weight. CONCLUSION: A low-cost program offering treatment of indefinite duration produced large long-term weight losses and may be suitable for widespread replication.

Adult↗

Racial differences in visceral adipose tissue but not anthropometric markers of health-related variables.

This study sought to determine whether visceral adipose tissue (VAT) and/or its anthropometric surrogates could significantly predict health-related variables (HRV) in overweight Caucasian (CC) (n = 36) and African-American (AA) (n = 30) women. With the use of magnetic resonance imaging, findings showed significantly higher volume and area of VAT (P < 0.0001 for both) as well as higher triacylglycerol (P = 0.009) in CC compared with AA women. Furthermore, VAT volume, race, and VAT volume x race interaction could significantly predict triacylglycerol (P = 0.0094), high-density lipoprotein cholesterol (P = 0.0057), insulin (P = 0.0002), and insulin resistance (P < 0. 0001). Additionally, the VAT volume x race interaction for insulin (P = 0.040) and insulin resistance (P = 0.003) was significant. In a separate analysis, waist circumference and race predicted the identical variables. Our results support the use of volume or area of VAT in predicting HRV in CC women; however, its use in AA women appears limited. In contrast, waist circumference can provide a suitable VAT alternative for both CC and AA women; however, VAT clearly represents the more powerful predictor.

Adipose Tissue↗

Evaluation of formalin-fixed paraffin-embedded tissues obtained from vaccine site-associated sarcomas of cats for DNA of feline immunodeficiency virus.

OBJECTIVE: To evaluate the use of a polymerase chain reaction (PCR) method for detection of feline immunodeficiency virus (FIV) DNA, using formalin-fixed paraffin-embedded (FFPE) tissues, and to use this method to evaluate tissues obtained from vaccine site-associated sarcomas (VSS) of cats for FIV DNA. SAMPLE POPULATION: 50 FFPE tissue blocks from VSS of cats and 50 FFPE tissue blocks from cutaneous non-vaccine site-associated fibrosarcomas (non-VSS) of cats. PROCEDURE: DNA was extracted from FFPE sections of each tumor and regions of the gag gene of FIV were amplified by a PCR, using 3 sets of primers. Sensitivity of the method was compared between frozen and FFPE tissues, using splenic tissue obtained from a cat that had been experimentally infected with FIV. RESULTS: We did not detect FIV DNA in VSS or non-VSS tissues. Sensitivity of the PCR method was identical for frozen or FFPE tissues. CONCLUSIONS AND CLINICAL RELEVANCE: It is possible to detect FIV DNA in FFPE tissues by use of a PCR. We did not find evidence to support direct FIV involvement in the pathogenesis of VSS in cats.

Animals↗

Mutational analysis of tumor suppressor gene p53 in feline vaccine site-associated sarcomas.

OBJECTIVES: To investigate the role of tumor suppressor gene p53 mutation in feline vaccine site-associated sarcoma (VSS) development and to evaluate the relationship between p53 nucleotide sequence and protein expression. SAMPLE POPULATION: Formalin-fixed paraffin-embedded tissues of 8 feline VSS with dark p53 immunostaining (high p53 expression) and 13 feline VSS with faint or no staining (normal p53 expression). PROCEDURE: DNA was extracted from neoplastic and normal tissue from each paraffin block. The following 3 regions of the p53 gene were amplified by polymerase chain reaction: 379 base pair (bp) region of exon 5, intron 5, and exon 6, 108 bp region of exon 7, and 140 bp region of exon 8. Amplified p53 products were sequenced and compared with published feline p53. The p53 mutations identified were correlated with p53 mutations predicted by immunostaining. RESULTS: Neoplastic cells of 5 of 8 (62.5%) VSS that had high p53 expression harbored single missense mutations within the p53 gene regions examined. The p53 gene mutations were not detected in the 13 tumors with normal p53 immunostaining. Nonneoplastic tissues adjacent to all 21 VSS lacked mutations of these p53 gene regions. CONCLUSIONS: The p53 gene mutations were restricted to neoplastic tissue and, therefore, were unlikely to predispose to VSS. However, p53 mutations may have contributed to cancer progression in 5 of the 21 VSS. There was very good (kappa quotient = 0.67 with a confidence limit of 0.3 to 1.0), although not complete, agreement between prediction of mutation by p53 immunostaining and identification of mutations by sequencing of key p53 gene regions.

Animals↗

Rat-2 fibroblasts express specific adrenomedullin receptors, but not calcitonin-gene-related-peptide receptors, which mediate increased intracellular cAMP and inhibit mitogen-activated protein kinase activity.

Rat-2 fibroblasts demonstrate specific binding of 125I-labelled rat adrenomedullin (KD=0.43 nM; Bmax=50 fmol/mg of protein) in the absence of 125I-labelled calcitonin-gene-related peptide (CGRP) binding. Therefore Rat-2 cells were used to examine the pharmacology and signal transduction pathways of adrenomedullin receptors. We examined the effects of adrenomedullin, the CGRP receptor antagonist CGRP-(8-37) and the amylin antagonists AC187 and AC253 on receptor binding and cAMP production. AC253, AC187 and CGRP-(8-37) inhibited 125I-adrenomedullin binding, with respective IC50 values of 25+/-8, 129+/-39 and 214+/-56 nM. Adrenomedullin dose-dependently increased intracellular cAMP (approximate EC50=1.0 nM). CGRP-(8-37), AC253 and AC187 antagonized adrenomedullin-stimulated cAMP production at micromolar concentrations. Using kinase-substrate assays, Mono Q FPLC and 'phospho-specific' Western blotting, we found that adrenomedullin alone abolished basal mitogen-activated protein kinase (MAPK) activity and dose-dependently inhibited platelet-derived-growth-factor-stimulated MAPK activity. Radioimmunoassay for adrenomedullin of media from Rat-2 cells showed a linear release of adrenomedullin-like immunoreactivity of 3.1 fmol/h per 2x10(6) cells. Gel-filtration chromatography showed that this adrenomedullin-like immunoreactivity co-eluted with synthetic rat adrenomedullin. Northern blotting with a rat adrenomedullin cDNA probe was used to confirm the presence of adrenomedullin mRNA. However, neither Northern blotting nor reverse transcriptase-PCR showed the presence of the cloned adrenomedullin receptor (L1). We conclude that the Rat-2 cell line expresses a specific adrenomedullin receptor (coupled to cAMP production and regulation of MAPK) and secretes adrenomedullin, which may participate in a regulatory control loop.

Animals↗

The relationship between fat distribution and coronary risk factors in sedentary postmenopausal women on and off hormone replacement therapy.

The purpose of this study was to examine the relationship between fat distribution and coronary risk factors (CRF) in sedentary overweight postmenopausal women both on and off hormone replacement therapy (HRT). Medical records and information were abstracted from nonsmoking women entering a weight loss program. A total of 33 women on HRT (mean age=50.12+/-5.2) and 51 nonusers (mean age=52.52+/-7.8) fulfilled subject eligibility requirements and were included in the data analysis. Results showed a significantly lower waist-to-hip ratio (WHR) (p=0.009) and waist (p=0.010) and greater levels of high-density lipoprotein cholesterol (HDL-C) (p=0.035) in HRT users than in nonusers. After converting correlations to standard Z-scores and performing z-tests, the correlation between total cholesterol (T-Chol) and WHR was significantly greater in nonusers than in HRT users (p=0.038). A multiple regression analysis showed differences between groups in the ability of age and anthropometric variables to predict CRF. Although T-Chol could be predicted in nonusers (r2=0.24; p=0.011), very low-density lipoprotein cholesterol (VLDL-C) and systolic blood pressure (SBP) could be significantly predicted in HRT users only (r2=0.28, p=0.055 and r2=0.40, p=0.005 for VLDL-C and SBP, respectively). These data suggest that there are differences between HRT users and nonusers in predictors of CRF, central adiposity, HDL-C, and the relationship between WHR and T-Chol. It is concluded that the significantly lower levels of central adiposity observed in HRT users may have clinical benefits with regard to CRF.

Adipose Tissue↗

Clinical predictability of the waist-to-hip ratio in assessment of cardiovascular disease risk factors in overweight, premenopausal women.

The waist-to-hip ratio (WHR) is one of the most commonly used anthropometric measures to indicate a central obesity pattern and an increased risk of cardiovascular disease in normal-weight women. Although the American Heart Association has reported that a WHR >0.80 be used to indicate increased risk of cardiovascular disease in women, the present study assessed the WHR above which is seen elevations in cardiovascular disease risk factors in a sample of overweight women. Using data from 240 women aged 27.5-47.5 y enrolled in a university weight-loss program, we determined WHR quartiles: <0.80, 0.80 to <0.84, 0.84 to <0.90, and > or =0.90. Subjects were placed into high-risk categories for cardiovascular disease on the basis of age- and population-defined norms. Women had an increased likelihood of elevated VLDL cholesterol, triacylglycerol, diastolic blood pressure, and composite risk (ie, having > or =4 cardiovascular disease risk factors) and an increased risk of having low concentrations of HDL at a WHR > or =0.90. All aforementioned variables had a significant odds ratio at a WHR > or =20.90 after adjustment for smoking, whereas elevated VLDL, triacylglycerol, and diastolic blood pressure were observed at this WHR after adjustment for a body mass index (in kg/m2) < or > or =35. Only 2 variables, VLDL and triacylglycerol, had a significant odds ratio at a WHR <0.90 before and after adjustment for BMI and smoking. These data suggest an upward shift in the critical threshold for WHR to > or =0.90, at which point there was an elevation in cardiovascular disease risk factors in already overweight women. This trend persisted regardless of whether the women smoked or whether their body mass index was < or > or =35.

Adolescent↗