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Biomedical subjects

K Smith

Publications and source records attributed to K Smith.

At least 271 records · Page 15Linked to original sources
PubMed1995

Regulation of Wnt5a mRNA expression in human mammary epithelial cells by cell shape, confluence, and hepatocyte growth factor.

The Wnts are a family of genes with a role in cell fate and morphological development in numerous embryonic and adult tissues. In mouse mammary tissue a subset of the Wnts have a function in the normal development of the gland, and aberrant expression of Wnts normally silent in this tissue causes mammary carcinomas. We have previously shown that Wnt5a expression is elevated in the epithelial component of proliferative lesions of human breast and have therefore examined the regulation of Wnt5a mRNA expression in the human mammary epithelial cell line HB2, which has a luminal phenotype and thus represents the most commonly transformed cell type in human breast cancer. Wnt5a was up-regulated 30-fold at confluence. This up-regulation was induced specifically by confluence and not by the growth arrest that accompanied it. In addition, Wnt5a was down-regulated 3-fold by changes in cell shape associated with the transition from growth on a two-dimensional surface (flat cell morphology) to growth in three-dimensional gels (spherical cell morphology). Cytoskeletal disruption with non-toxic doses of colchicine also induced a spherical morphology and brought about a dose-dependent down-regulation of Wnt5a. Wnt5a was also down-regulated 10-fold during the hepatocyte growth factor-induced branching of HB2 cell aggregates in collagen gels. The down-regulation of Wnt5a preceded the branching process. A similar result was obtained with primary human breast epithelial populations and the breast cancer cell line MDA468. We conclude that regulation of Wnt5a expression is a down-stream effect of signaling by hepatocyte growth factor. These results are consistent with a role for Wnt5a in mammary epithelial cell motility and are in accord with Xwnt5a's function in embryonal cell migration. If Wnt5a's function in human mammary epithelial cells is similar to that of Xwnt5a, its up-regulation at confluence may be a mechanism for inhibition of cell migration beyond confluence.

Breast↗
PubMed1995

An investigation of methods for enriching trophoblast from maternal blood.

Trophoblast deportation is known to occur in normal human pregnancy, but it is not yet clear whether these cells routinely enter the maternal peripheral circulation and are available as a source of fetal DNA for non-invasive prenatal diagnosis of genetic disorders. To resolve this issue requires an efficient method of enriching trophoblast from maternal blood combined with a means to confirm its identity. Five different techniques were tested on ten retroplacental blood samples to determine the most sensitive and operator-efficient method. Lysis of red cells alone gave the best recovery of trophoblast but had to be discounted, together with Ficoll density gradient centrifugation, due to the very low purity and the excessive time required. Fluorescence-activated cell sorting (FACS) of pre-enriched trophoblast resulted in the lowest recovery rate (8 per cent) despite a 3250-fold enrichment and a very high purity. Immunomagnetic beads (Dynabeads) coated with anti-CD16 antibody proved to be the best method for the subsequent immunocytochemical characterization of deported trophoblast. However, IO beads coated with anti-CD45 antibody may be more useful for isolating trophoblast for prenatal diagnosis due to the high purity, enrichment (32-fold), and recovery rate (78 per cent) obtained with this method.

Cell Count↗
PubMed1995

Expression of messenger RNA for amphiregulin, heregulin, and cripto-1, three new members of the epidermal growth factor family, in human breast carcinomas.

The expression of amphiregulin (AR), heregulin (HRG), and cripto-1 (CR-1) mRNA transcripts was assessed in 60 human primary breast carcinoma. AR and HRG transcripts were expressed respectively in 58% and 25% of the carcinomas as measured by Northern blot analysis. CR-1 mRNA was found in 77% of the carcinomas using Reverse Transcriptase-PCR analysis. Coexpression of two or three of these peptides was observed in several specimens. There was no significant association between AR, HRG, and CR-1 expression and nodal status, EGF receptor, or c-erbB-2 protooncogene expression in these tumors. However, a significant association between AR expression and estrogen receptor positivity was observed.

Amphiregulin↗
PubMed1995

Plasmodium yoelii in mice: differential induction of cytokine gene expression during hyporesponsiveness induction and restimulation.

Acute Plasmodium yoelii murine malaria is associated with a marked depression of splenic T cell responses. The present study was undertaken to address the question if a defect in T cell proliferation results from a relative increase of a non-T cell population in the spleen or real biological changes occurring in T cells of the spleen after infection. When animals were acutely infected, the splenic cells responded poorly to cross-linked anti-CD3 mAb, Con A, and PWM stimulation. At this stage, a very limited array of cytokine was expressed. We failed to detect the transcripts for IL-2R p55, IL-2, IL-6, IL-10, and IFN-gamma in mice with acute P. yoelii malaria irrespective of the number of splenocytes subjected to RT-PCR. In contrast, late in the infection when mice cleared the parasites and became resistant to reinfection, mRNAs for the above cytokines as well as for IL-4, IL-5, GM-CSF, and TNF-alpha were detectable. During this late phase of infection, lymphocytes proliferated vigorously in response to TCR- and T cell mitogen-mediated stimulation. Surprisingly, during an early phase (as early as 3 days postinfection) with low parasitemia, before the establishment of T cell unresponsiveness, a broad array of cytokine expression including IL-2 and IFN-gamma expression as well as marked lymphoproliferative response upon T cell mitogen- and TCR-mediated stimulation was observed. When the expression of cytokine gene in freshly isolated (ex vivo) splenocytes from P. yoelii-infected animals was investigated, a similar pattern of cytokine profile was detected. We devised a methodology in which RNA from an increasing number of splenocytes (ranging from 1 to 16 million) was used to compensate for any difference in the frequency of splenic T cells between immune and acutely infected mice and to augment target molecules which could be measured simultaneously by PCR. The data presented in this study led us to speculate that "anergy" or relative increase of a non-T cell population cannot account solely for the T cell unresponsiveness in the acute phase of infection. We suggest that inactivation or/and ablation of reactive T cells may explain T cell hyporesponsiveness during acute malaria.

Animals↗
PubMed1995

Does preeclamptic pregnancy increase fetal-maternal hemorrhage?

Since pathologic changes of the placenta have been found in preeclamptic pregnancies, a relationship between fetal-maternal hemorrhage and preeclampsia was investigated. Sixty-two women with singleton pregnancies in the third trimester were studied. Thirty-one of these women with preeclampsia were matched with 31 normotensive healthy pregnant women. Maternal serum levels of alpha-fetoprotein (MSAFP) and Kleihauer-Betke (KB) test were determined to reflect the degree of fetal-maternal hemorrhage. There were no significant differences in MSAFP levels, MSAFP to creatinine ratio, or the appearance of fetal cells as measured by the KB test between preeclamptic pregnancies and matched controls. Our data do not suggest that fetal-maternal hemorrhage is increased in pregnant women with preeclampsia.

Adult↗
PubMed1995

Reliance by gay men and intravenous drug users on friends and family for AIDS-related care.

A group of gay-identified men (n = 81) and intravenous drug users (n = 88) diagnosed with AIDS in San Francisco were interviewed regarding their use of friends and family to meet their care needs. Analytic of quantitative data revealed that gay men relied more than did IDUs on friends for care. Neither group relied primarily on their families for care. Analysis of the qualitative data identified five primary barriers to care. First, many people with AIDS are not accustomed to asking for help and often avoid it when possible. Second, the social stigma surrounding AIDS sometimes leads to isolation. Third, some people with AIDS have kin with health problems of their own, thereby sometimes compromising this potential source of care. Fourth, the AIDS epidemic has devastated identifiable sub-populations, leaving surviving members of these groups emotionally exhausted and sometimes unable to provide as much help as they might have liked. Finally, some respondents choose to voluntarily cut themselves off from 'supportive' relationships that they perceive to be destructive now that they have been diagnosed with a fatal illness. Professional care providers and health care planners should be aware of dynamics within informal care networks of people with AIDS that may leave patients without necessary care.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Effect of gamma-irradiation on the effector function of T lymphocytes in microbial control.

A chlamydial-specific T cell clone, capable of inhibiting the growth of infectious Chlamydia in vivo and in vitro, was employed to investigate the effect of gamma-irradiation on the ability of effector T cells to control infections. Clone 2.14-0 (CD4+), specific for the Chlamydia trachomatis biovar agent of mouse pneumonitis (MoPn), was irradiated with varying doses (0, 2.5, 5.0, 10.0, 20.0 and 40.0 Gy) and its biological functions and ability to inhibit the intraepithelial growth of MoPn were assessed. The results revealed that although gamma-irradiation drastically reduced the proliferative response of the clone to antigen, it did not affect the phenotype and the effector function of inhibiting chlamydial growth. The preservation of anti-chlamydial function after gamma-irradiation correlated with the retention of IFN-gamma and TNF-alpha secretion in response to antigenic stimulation. We conclude that the biologic functions of T cells requiring proliferation and differentiation are more likely to be adversely affected by gamma-irradiation on the short-term, but the effector functions, possibly associated with cytokines and cytolysis, may be preserved among persisting effector T cells in an irradiated individual.

Animals↗
PubMed1995

Further chemotherapy versus low-dose involved-field radiotherapy as consolidation of complete remission after six cycles of alternating chemotherapy in patients with advance Hodgkin's disease. German Hodgkins' Study Group (GHSG).

OBJECTIVE: It was the aim of this prospective randomized multicenter study to compare chemotherapy and radiotherapy as consolidation treatments in patients achieving complete remission (CR) after 6 cycles of doxorubicin-containing chemotherapy in advanced-stage Hodgkin's disease (HD). METHODS: A total of 288 previously untreated patients aged 18-60 years with stage IIIB or IV HD received induction chemotherapy with 3 X (COPP + ABVD). Patients achieving CR were eligible for randomisation to either 20 Gy radiotherapy to initially involved fields (RT-arm) or to an additional 1 X (Copp + ABVD) (CT-arm ). Patients with nodal PR were allocated to more intense radiotherapy (IRT-arm: 20 Gy IF, 40 Gy to persisting tumor). Four patients with persisting organ involvement after induction received salvage chemotherapy. RESULTS: Of 288 patients, 171 (59%) achieved CR after induction chemotherapy. Of these, 100 patients were successfully randomized to RT or CT. In the CT arm relapses were observed on 10 of 49 patients compared with 13 of 51 patients in the RT arm (p = n.s.). Fifty patients refused randomisation and for them a treatment was chosen, and 21 patients refused any further treatment. Of these 21 patients with no consolidation therapy, 9 relapsed, indicating an approximately 3-fold increased relapse risk compared with those receiving either of the consolidation therapies. No relapse was observed in initially involved lung or liver sites. Adverse prognostic factors for freedom from treatment failure and survival were low hemoglobin and large mediastinal mass at initial presentation. CONCLUSIONS: No statistically significant differences in treatment efficacy were detected between 20 Gy IF radiotherapy and 1X (COPP + ABVD) chemotherapy following CR after six cycles of alternating chemotherapy in patients with advanced-stage HD. However, limited observations in a non-randomized cohort indicate that patients without consolidation treatment of CR after 6 cycles of chemotherapy may have an elevated risk of relapse.

Adolescent↗
PubMed1995

Anthropometric optical surface imaging system repeatability, precision, and validation.

Disciplines using human body surface dimensions require accurate, repeatable measurements. This study presents a design for the analysis of repeatability, precision, and validation of a new anthropometric device. This model enables estimation of the proportion of the total variation attributable to each level of data collection. This model is applied to an analysis of repeatability, precision, and validation of the Cencit Imaging System, a new optical surface scanner. Twenty-seven facial landmarks were marked on 10 men and 10 women at two measurement sessions. Two images were scanned during each session, and each image was digitized twice. The Cencit Imaging System results were compared with a previously validated digitizer. The Cencit Imaging System was found to produce accurate, highly repeatable images. Much of the error in this study is attributable to human error in marking landmarks on the subjects. The new imaging system will prove useful in a variety of anthropometric applications.

Anthropometry↗
PubMed1995

Urinary basic fibroblast growth factor in patients with bladder cancer and benign prostatic hypertrophy.

OBJECTIVE: To investigate the role of urinary measurements of an angiogenic factor, basic fibroblast growth factor (bFGF), in the assessment of patients with bladder cancer. PATIENTS AND METHODS: Urine from 83 patients was assayed using a commercially available ELISA for bFGF. Thirty-eight patients had a bladder tumour and 21 had a history of bladder cancer but no disease at the time of testing. Twenty-four patients acted as controls, 16 of whom were about to undergo transurethral resection of the prostate (TURP) for benign prostatic hypertrophy (BPH) and eight who had no urological disease. RESULTS: Median urinary bFGF was higher in patients with active bladder cancer than in those with a clear cystoscopy (5.20 and 2.13 ng/g creatinine, respectively; P < 0.005). Median urinary bFGF was also elevated in patients about to undergo TURP (4.52 ng/g creatinine). Using a threshold value of 6.0 ng/g creatinine, the sensitivity of the test for detecting cancer was 42% and specificity was 88%. At a threshold value of 4.0 ng/g the sensitivity was 62% and the specificity 70%. CONCLUSION: The relationship between urinary basic FGF and the presence of bladder cancer was significant. The test is not sufficiently sensitive or specific to use as a screening test for bladder cancer but may be very useful in monitoring the effectiveness of systemic therapies in bladder cancer. Elevated levels of bFGF in the urine of patients about to undergo TURP suggests a role for bFGF in the pathogenesis of BPH.

Aged↗
PubMed1995

Investigation of the subtype of alpha 2-adrenoceptor mediating prejunctional inhibition of cardioacceleration in the pithed rat heart.

1. We have investigated the subtype of alpha 2-adrenoceptor mediating prejunctional inhibition of cardioacceleration in the pithed rat heart in comparison with alpha 2-adrenoceptor ligand binding sites. 2. In pithed rats, prejunctional alpha 2-adrenoceptors were investigated in terms of the ability of alpha 2-adrenoceptor antagonists to shift the inhibitory potency of the alpha 2-adrenoceptor agonist, xylazine, against the tachycardia to a single electrical stimulus given via the pithing rod. 3. Antagonist potency at prejunctional alpha 2-adrenoceptors in pithed rat heart was correlated with antagonist affinity at alpha 2-adrenoceptor ligand binding sites in membranes of rat kidney and submandibular gland labelled with [3H]-yohimbine. 4. The correlation with the prejunctional alpha 2-adrenoceptor in pithed rat heart was best for the alpha 2D-adrenoceptor ligand binding site of rat submandibular gland (r = 0.98, n = 10, P < 0.0001), as compared to correlations with the alpha 2A-adrenoceptor ligand binding site of human platelet (r = 0.90, n = 9, P < 0.001), the alpha 2B-adrenoceptor ligand binding site of rat kidney (r = 0.82, n = 10, P < 0.01) and with published results for the alpha 2C-adrenoceptor ligand binding site (r = 0.48, n = 6, NS). 5. It is concluded that the functional prejunctional alpha 2-adrenoceptor of pithed rat heart closely resembles the alpha 2D-adrenoceptor ligand binding site of rat submandibular gland.

Adrenergic alpha-Agonists↗
PubMed1995

Fabrication of vascular replicas from magnetic resonance images.

Image processing and Computer Numerical Controlled (CNC) machining techniques have been used to prepare a large-than-life investment cast of an aortic bifurcation from magnetic resonance images of a replica of the vessel. The technique will facilitate experimental studies of vascular fluid dynamics and permit the in vitro reproduction of flows in living subjects.

Animals↗
PubMed1995

Gut mucosal protein synthesis measured using intravenous and intragastric delivery of stable tracer amino acids.

We measured the rates of mucosal protein synthesis during the simultaneous delivery of [1-13C]leucine and [1-13C]valine delivered either intragastrically or intravenously to investigate any influence of the route of supply of the tracers. Dependent on the route, there were marked differences in the gradient of labeling between the plasma and intramucosal leucine and valine; i.e., for intravenous tracers the ratio was 1.73 +/- 0.16, but for intragastric tracers it was 0.65 +/- 0.12 (P < 0.05). Incorporation of intravenous tracer into mucosal protein was linear with time, and irrespective of tracer route, the calculated fractional rates of protein synthesis were identical when based on the intracellular labeling of the leucine or valine tracer, i.e., with intravenous 2.58 +/- 0.32%/h and with intragastric 2.45 +/- 0.36%/h. The results demonstrate that a robust and reproducible method of measurement of gastrointestinal mucosal protein synthesis has been developed and that use of either intragastric or intravenous routes of tracer administration gives comparable results. The high rates measured suggest that the gastrointestinal mucosa contributes substantially to whole body protein synthesis in normal healthy subjects.

Adult↗
PubMed1995

Effect on breathing of neuronal dysfunction in the caudal ventral medulla of goats.

It has been reported that the caudal ventrolateral medulla (VLM) is important in central chemoreception and the control of breathing. The objective of this study was to determine in adult goats the effects on breathing of neuronal dysfunction of this caudal VLM region (area L; caudal to rostral hypoglossal nerve rootlet). Thermodes were chronically implanted on the VLM to cool neurons and thereby cause neuronal dysfunction. During awake and (halothane) anesthetized states, cooling the caudal VLM for 20 s to 20 degrees C did not alter breathing (P > 0.10). However, between 20 and 30 s of cooling and during recovery from cooling 0-4 mm caudal to the rostral hypoglossal rootlet, there was a 12 (awake) to 25% (anesthetized) increase (P < 0.05) in breathing. This tachypneic hyperpnea was uniform over conditions of eucapnia, hypercapnia, and hypoxia and resulted from reduced inspiratory time that increased frequency. We conclude that in goats inhibitory neurons are located in area L and the lateral caudal ventral medulla.

Anesthesia↗
PubMed1995

Prediction of 12-month neurodevelopmental outcome from a 6-month neurologic examination in premature infants.

This study examined whether a neurologic examination at 6 months of age is predictive of neurodevelopmental outcome at 12 months in very-low-birth-weight (VLBW) infants. A neurologic examination and the Bayley Scales of Infant Development were performed at 6 and 12 months with VLBW infants and full-term (FT) controls. VLBW infants were categorized based on early medical complications. High-risk (HR) infants had diagnoses of bronchopulmonary dysplasia, pulmonary immaturity, grade III or IV intraventricular hemorrhage, and/or periventricular leukomalacia. VLBW infants with other diagnoses were placed in the low-risk (LR) group. Total neurologic scores (NS) improved over time for all three groups but improved more for HR infants, who had more abnormal NS at both time points; NS at 6 months predicted neurologic and developmental scores at 12 months for all three groups, but the relation between 6- and 12-month outcomes was strongest for the HR infants. The neurologic examination may be helpful in assessing VLBW infants' need for referral to early childhood intervention programs.

Brain↗