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Biomedical subjects

M L Smith

Publications and source records attributed to M L Smith.

At least 163 records · Page 9Linked to original sources
PubMed1996

Factor structure of mental health measures.

This study investigated the factor structure of 18 scales that measure personal growth, subjective well-being, stress-resistant personality, self-deceptive positivity, and demographics. The sample of 338 persons was drawn from university students and community residents. A principal-components analysis with oblique rotation found a large factor for measures of subjective well-being as well as smaller factors for measures of personal growth, gender and age, and personality integration and education. Results provided support for the hypothesis that subjective well-being and personal growth are related, but not identical, constructs. Implications are discussed.

Adult↗
PubMed1996

Gas chromatographic/mass spectrometric detection of narcotine, papaverine, and thebaine in seeds of Papaver somniferum.

In addition to codeine and morphine, three more compounds: narcotine (noscapine), papaverine, and thebaine were found in Indian and Netherlands poppy seeds (Papaver somniferum L). The compounds were detected by a GC/MS technique and the identities were confirmed by comparing retention times and ion ratios with the known references. The concentrations of codeine, morphine, thebaine, papaverine, and narcotine were 44, 167, 41, 67, and 230 micrograms/g in Indian poppy seeds, and were 1.8, 39, 1.0, 0.17, 0.84 micrograms/g in Netherlands poppy seeds, respectively. Because these compounds may be urinary products after poppy seed consumption, the lowest detectable concentrations of codeine, morphine, thebaine, papaverine, and narcotine in urine are of interest and were found to be 4, 4, 5, 0.4, and 4 ng/ml, respectively. The detection of urinary narcotine, papaverine, or thebaine may be utilized to differentiate poppy seed consumption from illicit codeine, morphine, or heroin use.

Gas Chromatography-Mass Spectrometry↗
PubMed1996

Inhibition of cancer cell growth by internalized immuno-histone conjugates.

MAb NS 88 directed against breast cancer cells, which is internalized and translocated to the cell nucleus, was conjugated with histone and labeled with 125I. 125I-MAb-histone complexes (M(r) 250,000) were internalized by breast and cervical cancer cells and localized in the cytoplasm and chromatin. Electrophoretic analysis of the cells extracted from the conjugates revealed the same molecular weights of the cytoplasmic and chromatin complexes as those of the native conjugate. Nicotine (0.1%), which suppresses lysosomal degradation, stabilized the conjugates within the cell and prolonged the presence of nondegraded complexes inside the cytoplasm and chromatin from 1 day to at least 3 days. MAb-histone complexes, but not MAb alone, inhibited RNA synthesis and proliferation of cervical and breast cancer cells. A new application of internalized MAbs as the vehicles for protein inhibitors of transcription or replication is discussed.

Antibodies, Monoclonal↗
PubMed1996

Abrogation of p53 function affects gadd gene responses to DNA base-damaging agents and starvation.

The tumor suppressor p53 is required for induction of its downstream effector genes such as GADD45 and CIP1/WAF1 by ionizing radiation (IR). This response is probably mediated through defined p53 binding sites located in the promoter of CIP1/WAF1 and in the third intron of GADD45. In contrast, the gadd gene stress response to base-damaging agents, such as methylmethane sulfonate (MMS) or UV radiation, or medium depletion (starvation) occurs in all mammalian cells examined to date regardless of p53 status for both GADD45 and also GADD153, which is not IR-responsive in many lines with functional p53. These agents strongly induce the p53 protein and raise the possibility that, although p53 is not required for the typical "gadd" response to these agents, p53 may contribute to these non-IR stress responses. This possibility was confirmed by the finding that disruption of p53 function by transfection with dominant-negative vectors expressing HPV E6, mutant p53, or SV40 T Ag reduced the induction of GADD45 and GADD153 as measured by increases in mRNA and protein levels in human lines with wild-type p53. Similarly, induction of these genes by MMS or UV radiation was consistently stronger in the parental mouse embryo fibroblasts compared to cells derived from mice where both p53 alleles had been deleted. Similar qualitative responses were also seen for CIP1/WAF1. In agreement with reduced induction of p53-regulated genes, the G1 checkpoint activated by MMS or UV radiation was markedly abrogated in p53-wt human MCF-7 breast carcinoma cells by E6 expression. Interestingly, induction of reporter constructs driven by the GADD45 or GADD153 promoters was substantially reduced in human cells transfected with mutant p53 or E6 expression vectors or in cells lacking p53 following treatment with MMS, UV radiation, or starvation. Because neither promoter is inducible by IR, and neither contains a strong p53 binding site, these results indicate that p53 has a synergistic or cooperative role in these non-IR stress responses for both GADD45 and GADD153, and that this role is not mediated through identifiable p53-binding sites.

Animals↗
PubMed1996

Fat malabsorption in elderly patients with cardiac cachexia.

Malnutrition resulting from chronic congestive heart failure (cardiac cachexia, CC) is not uncommon and contributes to mortality and morbidity especially of elderly people. The aetiology of cardiac cachexia is probably multifactorial. We have assessed whether malabsorption of fat is associated with CC and if so whether it is due to small-bowel bacterial overgrowth. Three groups of subjects were studied: 29 (20 women) patients (mean age 76.1 years) with controlled congestive heart failure and weight loss (CC); 14 (seven women) patients (mean age 74.0 years) with controlled congestive heart failure and no weight loss (non-cachexia, NON-CC); and 29 (20 women) healthy controls (mean age 74.9 years). Fast absorption was quantified using the cumulative 6 h 14CO2 exhalation in the 14C-triolein breath test and small-bowel bacterial overgrowth was quantified using the cumulative 8 h 14CO2 exhalation in the 14C-glycocholic acid breath test. The cumulative 6 h 14CO2 exhalation in the triolein breath test was reduced in the CC group (p = 0.001) implying impaired fat absorption. There was no evidence of small-bowel bacterial overgrowth in any group. Impaired absorption of fat was related to the clinical severity of heart failure and its duration. Impaired fat absorption is associated with cardiac cachexia. It is not due to small-bowel bacterial overgrowth. The aetiology of fat malabsorption in heart failure requires further studies.

Aged↗
PubMed1996

Gastro-intestinal protein loss in elderly patients with cardiac cachexia.

Undernutrition resulting from chronic congestive heart failure (cardiac cachexia, CC) increases morbidity and mortality particularly in elderly people. The aetiology of CC is thought to be multifactorial. We have assessed the presence of gastro-intestinal protein loss in a group of patients with CC and a group of healthy age-and sex-matched controls. Gastro-intestinal protein loss was measured using the chromic chloride test in 29 patients with CC [mean age 76.1 (SD4.4) years] and 29 healthy controls [mean age 74.9 (SD 4.8) years]. The patients were undernourished in terms of anthropometric measurements compared to controls. The patients had a significantly lower mean ejection fraction [41.5(18.3)% vs. 65.5(2. 2)%] and higher mean pulmonary artery pressure [89.4(19.9)mmHg vs. 19.3(8.1) mmHg]. The recovery of radioactivity in a 5-day stool collection was similar in the two groups [patients vs. controls: 1. 0(0.7)% vs. 0.98(0.6)%, p=0.9]. These values are within the expected normal range. We conclude that gastro-intestinal protein loss is not a significant factor in the production of cardiac cachexia.

Aged↗
PubMed1996

PDGF AA as mediator in nicotine-dependent carcinogenesis.

Effect of nicotine on PDGF AA and PDGF BB interaction with cervical cancer SiHa cells was tested. [125I]PDGF AA was internalized by cells and accumulated in the cytoplasm and nucleus (chromatin). In the absence of nicotine, maximal accumulation of [125I]PDGF AA inside the cells occurred after 1 day of incubation, which was followed by a progressive degradation of the growth factor during the next 2, 3 and 5 days of cell exposure. In the presence or 0.001 or 0.01% nicotine, accumulation of [125I]PDGF AA was slightly higher than in the absence of nicotine, and maximal accumulation occurred after 2 days or incubation. In the presence of 0.1 % nicotine, maximal accumulation occurred after 5 days of incubation and was 20 and 14 times higher in the cytoplasm and chromatin, respectively. Nicotine-postponed degradation and increased nuclear accumulation of PDGF AA resulted in activation of RNA synthesis and cell proliferation. PDGF BB, which was not internalized by cells did not respond to nicotine treatment. The proposed mechanism of nicotine-PDGF AA co-carcinogenesis may involve inhibition of growth factor degradation at the lysosomal level and an increased chromatin accumulation of the non-degraded PDGF.

Becaplermin↗
PubMed1996

The product of the het-C heterokaryon incompatibility gene of Neurospora crassa has characteristics of a glycine-rich cell wall protein.

Filamentous fungi are capable of hyphal fusion, but heterokaryon formation between different isolates is controlled by specific loci termed het loci. Heterokaryotic cells formed between strains of different het genotype are rapidly destroyed or strongly inhibited in their growth. In Neurospora crassa, at least 11 loci, including the mating type locus, affect the capacity to form a heterokaryon between different isolates. In this report, we describe the molecular characterization of the vegetative incompatibility locus, het-C. The het-COR allele was cloned by genetically identifying the het-C locus in a chromosome walk, and the activity of clones containing the het-COR allele was tested in a functional transformation assay. The het-COR allele encodes a 966-amino acid polypeptide with a putative signal peptide, a coiled-coil motif and a C-terminal glycine-rich domain, similar to glycine-rich domains detected in various extracellular and structural cell envelope proteins. Both the coiled-coil and one-third of the glycine-rich carboxyl terminal domains were required for full het-COR activity. Mutants of het-COR were obtained by repeat-induced point mutation (RIP); these mutants were indistinguishable from wild type during vegetative growth and sexual reproduction but displayed dual compatibility with both of two mutually incompatible het-COR and het-cPA strains.

Alleles↗
PubMed1996

Escape from het-6 incompatibility in Neurospora crassa partial diploids involves preferential deletion within the ectopic segment.

Self-incompatible het-6OR/het-6PA partial diploids of Neurospora crassa were selected from a cross involving the translocation strain, T(IIL-->IIIR)AR18, and a normal sequence strain. About 25% of the partial diploids exhibited a marked increase in growth rate after 2 weeks, indicating that "escape" from het-6 incompatibility had occurred. Near isogenic tester strains with different alleles (het-6OR and het-6PA) were constructed and used to determine that 80 of 96 escape strains tested were het-6PA, retaining the het-6 allele found in the normal-sequence LGII position; 16 were het-6OR, retaining the allele in the translocated position. Restriction fragment length polymorphisms in 45 escape strains were examined with probes made from cosmids that spanned the translocated region. Along with electrophoretic analysis of chromosomes from three escape strains, RFLPs showed that escape is associated with deletion of part of one or the other of the duplicated DNA segments. Deletions ranged in size from approximately 70 kbp up to putatively the entire 270-kbp translocated region but always included a 35-kbp region wherein we hypothesize het-6 is located. The deletion spectrum at het-6 thus resembles other cases where mitotic deletions occur such as of tumor suppressor genes and of the hprt gene (coding for hypoxanthine-guanine phosphoribosyl-transferase) in humans.

Chromosome Walking↗
PubMed1996

One-step esterification of benzoylecgonine with dimethylformamide-dipropylacetal or dimethylformamide-diisopropylacetal in the presence of pyridine.

A simple procedure was developed to derivatize benzoylecgonine extracted from urine for subsequent confirmation by gas chromatography-mass spectrometry. The compound was esterified with dimethylformamide-dipropylacetal (DMF-DPA) or dimethylformamide-diisopropylacetal (DMF-DIPA) to the corresponding propyl and isopropyl esters. The optimum reaction condition was found to be heating the reaction mixture in the presence of pyridine at 100 degrees C for 30 min. The procedure is a one-step esterification followed by evaporation of excess reagents. When benzoylecgonine was extracted from urine using a solid-phase extraction technique and derivatized with this procedure, the compound was detected at a level as low as 10 ng/mL. Quantitation was linear over the concentration range 10-8000 ng/mL.

Acetals↗
PubMed1996

Valsalva's maneuver revisited: a quantitative method yielding insights into human autonomic control.

Seventeen healthy supine subjects performed graded Valsalva maneuvers. In four subjects, transesophageal echographic aortic cross-sectional areas decreased during and increased after straining. During the first seconds of straining, when aortic cross-sectional area was declining and peripheral arterial pressure was rising, peroneal sympathetic muscle neurons were nearly silent. Then, as aortic cross-sectional area and peripheral pressure both declined, sympathetic muscle nerve activity increased, in proportion to the intensity of straining. Poststraining arterial pressure elevations were proportional to preceding increases of sympathetic activity. Sympathetic inhibition after straining persisted much longer than arterial and right atrial pressure elevations. Similarly, R-R intervals changed in parallel with peripheral arterial pressure, until approximately 45 s after the onset of straining, when R-R intervals were greater and arterial pressures were smaller than prestraining levels. Our conclusions are as follows: opposing changes of carotid and aortic baroreceptor inputs reduce sympathetic muscle and increase vagal cardiac motor neuronal firing; parallel changes of barorsensory inputs provoke reciprocal changes of sympathetic and direct changes of vagal firing; and pressure transients lasting only seconds reset arterial pressure-sympathetic and -vagal response relations.

Adult↗
PubMed1996

Tinea capitis.

Explore the source record for details and available documents.

Administration, Oral↗
PubMed1996

Characteristics of postischemic seizures in hyperglycemic rats.

Normoglycemic animals subjected to 10-20 min of transient ischemia survive without major neurological symptoms, but incur delayed neuronal damage selectively affecting vulnerable neuronal populations. If the animals are hyperglycemic before ischemia is induced, cell damage develops more rapidly, and postischemic seizures appear after a delay of 18-24 h. This study was designed to assess whether the primary insult, i.e., transient ischemia in hyperglycemic animals, triggers early epileptogenic activity which 'matures' into clinical seizures, or if the seizures arise as a result of secondary events occurring after many hours of recirculation. EEG activity during 20-24 h of postischemic recirculation was recorded from electrodes implanted in the neocortex and hippocampus of freely moving rats which had been subjected to 10 min of ischemia under normoglycemic or hyperglycemic conditions. Normoglycemic animals showed a transient postischemic reduction of EEG amplitude and frequency, and sparse and temporary epileptiform activity. In contrast, hyperglycemic animals showed a more pronounced reduction of EEG amplitude and frequency, and early appearing epileptiform activity which was sustained, and ultimately transformed into overt electrographic seizures. The EEG changes were more pronounced in the neocortex than in the hippocampus. The results thus demonstrate that the initial ischemic insult, and not the secondary damage appearing many hours after the initiation of recirculation, triggers epileptiform activity that 'matures' into status epilepticus.

Analysis of Variance↗
PubMed1996

Diagnosis of osteomyelitis in neuropathic foot ulcers.

We reviewed all patients with a clinically infected foot ulcer attending a specialised neuropathic foot clinic. Neuropathy was confirmed by the inability to feel a 5.07 Semmes-Weinstein hair, areflexia and impaired vibration sense, as measured by a biothesiometer. Of 40 patients who attended the clinic over a two-year period, six with ischaemic ulcers were excluded. The remaining 34 had plain radiographs of the foot followed by a 99mTc-MDP bone scan. If the latter was positive, an 111In-labelled WBC scan was performed with planar and/or tomographic dual-isotope studies where appropriate. Bone and WBC scans were performed in 31 patients. In ten, isotope imaging showed infection localised to the soft tissues only and conservative treatment was successful in them all. Eighteen patients were treated surgically with excision of the involved bone, which was sent for culture and histological examination. Dual-isotope scans had a sensitivity of 93% and a specificity of 83%. 99mTc-MDP bone scans with the appropriate In-labelled WBC scans can reliably determine the site and extent of osteomyelitis in the neuropathic diabetic foot.

Bone and Bones↗
PubMed1995

Direct interaction of Gadd45 with PCNA and evidence for competitive interaction of Gadd45 and p21Waf1/Cip1 with PCNA.

We have previously shown (Smith et al., 1994) that antibodies raised against the growth arrest and DNA damage inducible protein Gadd45 co-precipitate proliferating cell nuclear antigen (PCNA), a protein involved in DNA replication and repair. Here we demonstrate that Gadd45 can directly bind to PCNA using a Far-western blotting approach. In this assay, a Gadd45 bacterial expression vector was modified to allow synthesis of purified 32P-labeled Gadd45 fusion protein. This protein was used to detect filter bound PCNA protein, while filter bound Gadd45 protein could also be detected by free PCNA molecules. Using recombinant proteins in conjunction with immunoprecipitation and immunoblotting, we show that Gadd45 competes with p21 for binding to PCNA and conversely, p21 blocks the ability of Gadd45 to bind PCNA. In addition, p21 appears to disrupt PCNA trimers whereas Gadd45 has a lesser effect. PCNA trimer disruption was also observed in UV-irradiated cells but not in repair-defective xeroderma pigmentosum group A (XP-A) cells.

Base Sequence↗
PubMed1995

Disruption of p53 function sensitizes breast cancer MCF-7 cells to cisplatin and pentoxifylline.

The possibility that appropriately designed chemotherapy could act selectively against p53-defective tumor cells was explored in MCF-7 human breast cancer cells. These cells were chosen because they have normal p53 function but are representative of a tumor cell type that does not readily undergo p53-dependent apoptosis. Two sublines (MCF-7/E6 and MCF-7/mu-p53) were established in which p53 function was disrupted by transfection with either the human papillomavirus type-16 E6 gene or a dominant-negative mutant p53 gene. p53 function in MCF-7/E6 and MCF-7/mu-p53 cells was defective relative to control cells in that there were no increases in p53 or p21Waf1/Cip1 protein levels and no G1 arrest following exposure to ionizing radiation. Survival assays showed that p53 disruption sensitized MCF-7 cells to cisplatin (CDDP) but not to several other DNA-damaging agents. CDDP sensitization was not limited to MCF-7 cells since p53 disruption in human colon carcinoma RKO cells also enhanced sensitivity to CDDP. Contrary to the other DNA-damaging agents tested, CDDP-induced DNA lesions are repaired extensively by nucleotide excision, and in agreement with a defect in this process, MCF-7/E6 and MCF-7/mu-p53 cells exhibited a reduced ability to repair a CDDP-damaged chloramphenicol acetyltransferase-reporter plasmid transfected into the cells. Therefore, we attributed the increased CDDP sensitivity of MCF-7 cells with disrupted p53 to defects in G1 checkpoint control, nucleotide excision repair, or both. The G2 checkpoint inhibitor pentoxifylline exhibited synergism with CDDP in killing MCF-7/E6 cells but did not affect sensitivity of the control cells. Moreover, pentoxifylline inhibited G2 checkpoint function to a greater extent in MCF-7/E6 than in the parental cells. These results suggested that, in the absence of p53 function, cancer cells are more vulnerable to G2 checkpoint abrogators. Our results show that a combination of CDDP and pentoxifylline is capable of synergistic and preferential killing of p53-defective tumor cells that do not readily undergo apoptosis.

Apoptosis↗
PubMed1995

Involvement of the p53 tumor suppressor in repair of u.v.-type DNA damage.

The tumor suppressor p53 plays a central role in the cellular responses to genotoxic stress. Besides its well known role in activation of the G1 checkpoint after exposure to agents like ionizing radiation and its role in apoptosis, the possibility exists that p53 may have additional roles, such as in DNA repair. For example, p53, is known to bind to single strand DNA such as would occur during repair events, and the proteins encoded by two p53-regulated genes have previously been found to bind to at least one protein involved in DNA damage processing including nucleotide excision repair (NER). NER is an important and versatile DNA repair mechanism, which is the major pathway for repair of u.v.-type lesions and damage by a variety of important carcinogens and mutagens. If components of the p53 pathway are involved in NER, then disruption of p53 function by mutations or expression of certain viral proteins could have important implications in carcinogenesis and cancer treatment. In the present study we show that disruption of normal p53 function in human colon carcinoma RKO cells with either the human papillomavirus E6 oncoprotein or a dominant-negative mutant p53 transgene results in reduced repair of u.v.-induced DNA damage. The E6 and mutant p53-containing cell lines demonstrated reduced repair of u.v.-induced DNA lesions in host cell reactivation experiments with reporter plasmids, and reduced repair in in vitro DNA repair assays. With this in vitro assay, extracts from the E6- and mutant p53-containing lines also showed loss of induced repair following cellular u.v.-irradiation. The reduced DNA repair activity of the transfected cell lines also correlated with reduced clonogenic survival following u.v.-irradiation. These results indicate that p53 and/or p53-regulated gene products function in the NER pathway and that this process is inducible by DNA damage.

Base Sequence↗