Search PubMed⌕ Search

Biomedical subjects

C M White

Publications and source records attributed to C M White.

At least 73 records · Page 4Linked to original sources
PubMed1998

At least four loci and gender are associated with susceptibility to the chemical induction of lung adenomas in A/J x BALB/c mice.

Four putative quantitative trait loci (QTLs) that influence susceptibility to the induction of lung adenomas by urethane in an F2 cross between A/J and BALB/cOlaHsd have been mapped. Following microsatellite typing of mice with resistant and susceptible phenotypes at 97 microsatellite marker loci, a major locus was identified on chromosome 18 with a lod score of 15. This was responsible for an 8- to 10-fold increase in tumor multiplicity in males and females, respectively, having the AA and CC genotypes at the D18Mit188 marker locus. It mapped close to Dcc (deleted in colorectal cancer). A locus on chromosome 4 (lod score 6.5) had the resistant allele in strain A/J and the susceptible allele in BALB/c, with a 14-fold difference in tumor multiplicity between mice of the AA and CC genotypes. This mapped close to the Cdkn2a (cyclin-dependent kinase inhibitor 2A) locus, which is commonly deleted in mouse lung tumors. Two loci with smaller effects (lod scores 3.03 and 3.25) were identified on chromosomes 1 and 11. There was also significant sexual dimorphism in tumor multiplicity both among 151 F2 hybrids and among 52 mice resulting from a backcross to strain A/J, with males having higher tumor counts than females.

Adenoma↗
PubMed1998

Catecholamines and their blockade in congestive heart failure.

The hemodynamic effects of sympathetic nervous system stimulation and the benefits of catecholamine blockade in patients with congestive heart failure (CHF) are discussed. Prolonged stimulation of the sympathetic nervous system promotes disease progression in patients with CHF. The level of circulating norepinephrine is the factor most closely correlated with prognosis. Long-term catecholamine stimulation of beta-receptors in the myocardium reduces the ability of catecholamines to improve cardiac contractility. CHF patients have higher vascular resistance (afterload) than healthy persons, increasing the strain on the heart. Also, beta 1-adrenergic activity stimulates renin release, which is deleterious in CHF. Clinical trials suggest that long-term (greater than one month), carefully dose-adjusted therapy with beta-blockers improves symptoms, ventricular ejection fraction, exercise time, and quality of life in patients with CHF, but it is unclear whether beta-blockers reduce mortality. Some patients cannot tolerate even the lowest starting dosages of beta-blockers, and withdrawal of these agents may result in clinical and hemodynamic deterioration. Carvedilol, which has beta-blocking, alpha-blocking, and antioxidant properties, is associated with a reduction in hospitalizations and symptoms and improvements in ejection fraction it also appears to reduce mortality, although confirmatory studies are needed. Initiation of carvedilol therapy can cause symptomatic and hemodynamic worsening in the short term, and some patients cannot tolerate it. Adrenergic blocking agents are important components of therapy for CHF. Carvedilol may prove useful in reducing symptoms and improving survival in these patients.

Adrenergic beta-Antagonists↗
PubMed1998

Recovery of rat skeletal muscles after partial denervation is enhanced by treatment with nifedipine.

Following partial denervation of adult rat skeletal muscle intact axons sprout to reinnervate denervated muscle fibres and increase their territory. The extent of this increase is limited and may depend on the ability of axon terminals to form and maintain synaptic contacts with the denervated muscle fibres. Here we tested the possibility whether reducing Ca2+ entry into presynaptic nerve terminals through dihydropyridine sensitive channels may allow more nerve-muscle contacts to be formed and maintained. Hindlimb muscles of adult Wistar rats were partially denervated by removing a small segment of the L4 or L5 spinal nerve on one side. A nifedipine-containing silastic rubber strip was subsequently implanted close to the partially denervated soleus or extensor digitorum longus (EDL) muscles in some animals. In control experiments silastic strips which did not contain nifedipine were used. Several weeks later isometric contractions were recorded, to determine the effect of (a) partial denervation and (b) nifedipine treatment on force output and motor unit numbers. The tension produced by nifedipine treated partially denervated muscles was 82% and 79% of the unoperated contralateral value for soleus and EDL, respectively. This was significantly greater than in untreated muscles, which only produced 61% and 48%, respectively. Mean motor unit force was also significantly larger with nifedipine treatment. Histological analysis revealed that a significantly larger proportion of the total number of muscle fibres remained in nifedipine-treated partially denervated muscles (soleus, 90% and EDL, 101%) compared with untreated muscles (soleus, 51% and EDL, 66%). Thus the number of neuromuscular contacts was increased with nifedipine treatment.

Animals↗
PubMed1998

Efficacy of intravenous granisetron in suppressing the bradycardia and hypotension associated with a rabbit model of the Bezold-Jarisch reflex.

This study investigated whether granisetron, a 5-HT3 receptor antagonist, can alter the Bezold-Jarisch reflex (i.e., hypotension and inappropriate heart rate slowing). A hemorrhagic rabbit model that has been shown to induce the Bezold-Jarisch reflex was used. In 11 rabbits (3.8 kg), catheters were placed in the carotid arteries one day before experimental hemorrhage. On the day of the study, the rabbits were given intravenous granisetron (50 micrograms/kg) or an equal volume of saline. Five minutes after administration of granisetron or saline, hemorrhage was induced by continuous blood withdrawal at 5 mL/min and blood pressure (BP) and heart rates were obtained at frequent intervals until systolic BP declined to 80 mmHg. Six rabbits received saline and five granisetron. An average of 77.6 mL +/- 16.4 mL of blood was removed in the group receiving granisetron (compared with 56.5 mL +/- 13.1 mL for the saline group) before achieving the target systolic BP of 80 mmHg. The group receiving granisetron demonstrated the same ability to increase their heart rate from baseline as the saline group. However, the granisetron group had a final heart rate that was closer to their maximal heart rate than the saline group. In this animal model, granisetron was significantly more effective at preventing inappropriate heart rate slowing and allowed significantly more blood to be removed before reaching the target blood pressure. This implies that granisetron may be effective in preventing vasovagal syncope, although further study should be carried out to verify these potentially interesting findings.

Animals↗
PubMed1998

Effects of paclitaxel on cytokine synthesis by unprimed human monocytes, T lymphocytes, and breast cancer cells.

Paclitaxel or Taxol has attracted a great deal of attention in recent years because of its immense success as a chemotherapeutic agent for numerous types of cancer. It is known that paclitaxel stabilizes microtubules, and this characteristic is the presumed primary mechanism for its antitumor activity. Recently, however, paclitaxel's ability to regulate gene expression, particularly in the murine system, has been reported by several groups. Here, we present research examining paclitaxel's ability to alter expression of the interleukin-1beta (IL-1beta) and IL-8 cytokines in primary human monocytes, T lymphocytes, and four human breast cancer cell lines: MCF-7, ZR-75-1, MDA-MB-468, and MDA-MB-231. This report shows for the first time that treatment with 5-50 microM paclitaxel increases steady-state levels of IL-1beta mRNA in unprimed human monocytes, MCF-7, and ZR-75-1 cells. Monocytes from eight donors in 16 experiments showed increased IL-1beta secretion upon treatment; however, the increase in IL-1beta production by monocytes was predicated on culturing in the absence of fetal bovine serum or in the presence of autologous human serum. In contrast to the IL-1beta results, paclitaxel did not have significant effects on IL-8 expression by monocytes, T lymphocytes, or the breast cancer cells. These data show a specific effect of paclitaxel on cytokine synthesis by both immune cells and cancer cells.

Antineoplastic Agents, Phytogenic↗
PubMed1998

The pharmacokinetics of intravenous testosterone in elderly men with coronary artery disease.

Intracoronary testosterone injections have recently been shown to possess coronary vasodilating effects. The same may be true for intravenous testosterone, but the pharmacokinetic and hemodynamic aspects need exploration before pharmacologic studies can begin. This trial determined the pharmacokinetic and hemodynamic properties of 300 microg of testosterone given intravenously. Degree of testosterone aromatization to 17-beta estradiol after exogenous administration and overall patient tolerability also were evaluated. Eleven elderly men with coronary artery disease participated in the study and were given 300 microg of testosterone intravenously over 10 minutes. Serum blood concentrations of testosterone and 17-beta estradiol were measured at baseline and then periodically. Testosterone serum concentrations were stripped and fit to a two-compartment model for all patients. The volume of distribution (Vdarea) was 80.36 +/- 24.51 L, and the elimination half-life was 55.93 +/- 23.06 minutes. No hemodynamic differences or side effects were noted. The serum concentrations of 17-beta estradiol were significantly increased from baseline beginning 5 minutes after infusion to the end of the study (180 minutes after infusion).

Aged↗
PubMed1997

Smad4 (homolog of human DPC4) and Smad2 (homolog of human JV18-1): candidates for murine lung tumor resistance and suppressor genes.

In this study we investigated the mouse mad-related genes, Smad4/Dpc4 and Smad2 (homolog of JV18-1), as candidates for involvement in lung tumor resistance and suppression. These genes are located in a region of mouse chromosome 18 that is syntenic with human 18q21.1, where several genes that are mutated in various cancers have been mapped. A newly identified murine lung tumor resistance locus, Par2 has also been mapped to this region of chromosome 18. We found no mutations in the coding regions of either gene in 11 lung tumors from B6CF1 (C57BL/6 x BALB/c) mice by RT-PCR and SSCP/RFLP, suggesting that these genes are not mutated in lung carcinogenesis in this strain. Moreover, loss of heterozygosity in this region of chromosome 18 was not detected in 28 lung adenocarcinomas from B6CF1 mice, 17 lung adenocarcinomas from B6C3F1 mice or 18 lung adenocarcinomas from AB6F1 mice. These data provide evidence that a 'classical' tumor suppressor gene for mouse lung carcinogenesis in these strains does not reside in this region. In order to investigate Smad4/Dpc4 and Smad2 as candidates for the Par2 resistance locus mapped to this region, we also sequenced the coding regions of both genes in cDNA from normal lungs of A/J, BALB/c and C57BL/6 inbred strains of mice. No polymorphisms were detected in the coding region of Smad4. In Smad2, two sequence polymorphisms were identified that are not in the conserved regions of the gene. Northern blot analysis revealed no differential expression in normal lung tissue among the three strains for either gene. Thus, in this study we found no evidence that either Smad4 or Smad2 represents the Par2 lung tumor resistance locus or is a lung tumor suppressor gene in the B6CF1 mice.

Animals↗
PubMed1997

Seizure resulting from a venlafaxine overdose.

OBJECTIVE: To report a case of venlafaxine overdose. CASE SUMMARY: A 40-year-old woman with major depression took an overdose of venlafaxine in an apparent suicide attempt. After the ingestion of 26 venlafaxine 50-mg tablets, the patient experienced a witnessed generalized seizure. She was admitted to the medical intensive care unit, venlafaxine was discontinued, and no further sequelae were seen. DISCUSSION: To our knowledge, this is the first reported case of venlafaxine overdose that resulted in a generalized seizure. Based on nonoverdose pharmacokinetics and pharmacodynamics of venlafaxine and the potential risks of available interventions, no emergent therapy was instituted. CONCLUSIONS: The venlafaxine overdose in our patient resulted in a single episode of generalized seizure but elicited no further sequelae.

Adult↗
PubMed1996

Taxol-dependent transcriptional activation of IL-8 expression in a subset of human ovarian cancer.

Taxol is important in the treatment of both primary and drug-resistant ovarian cancer. Although Taxol is known to stabilize microtubules and block cell mitosis, the effectiveness of this drug exceeds that of other antimitotic agents, suggesting it may have an additional mode of action. Stimulated by murine macrophage studies indicating cytokine induction by Taxol, we have investigated proinflammatory cytokine expression in a series of cell lines and recent explants of human ovarian cancer. Taxol induced secretion of interleukin (IL) 8 but not IL-6, IL-1alpha, or IL-1beta in 4 of 10 samples. Induction was dependent on transcriptional activation, and, in contrast to murine macrophage studies, was apparently independent of an active lipopolysaccharide signaling pathway. Confluent cultures secreted as much IL-8 as proliferating cells. Taxol did not induce IL-8 in breast carcinoma, endometrial stromal, or T-lymphocyte or monocyte cultures. We propose that the local expression of this chemokine in vivo may elicit a host response similar in effectiveness to that of cytokine gene therapy. These data are the first to suggest that a chemotherapeutic agent may have a direct effect on transcription of cytokine and/or growth factor genes in ovarian cancer, and that this effect may not be restricted to proliferating tumor cells.

Administration, Topical↗
PubMed1996

New definitions.

Explore the source record for details and available documents.

Community Health Nursing↗
PubMed1996

Cholestyramine ointment to treat buttocks rash and anal excoriation in an infant.

OBJECTIVE: To describe a novel treatment for perianal excoriation in an infant receiving a promotility agent. CASE SUMMARY: A 2-month-old boy with reflux, and regurgitation was treated with cisapride. Shortly after cisapride therapy he developed a rash on his buttocks and anal irritation that progressed in severity despite the use of numerous topical products and extended diaper-free periods. A topical cholestyramine ointment compound was prepared and administered, resulting in complete resolution within 3 days. DISCUSSION: Cisapride can decrease the gastrointestinal transit time, which can lead to less time for bile acid reabsorption in the distal ileum. If high concentrations of bile acids are contained in the stool, they can irritate the anus and buttocks in a manner similar to the skin irritation experienced by patients with ostomies. Cholestyramine, a bile acid sequestrant, can irreversibly bind the bile when applied topically and bring relief to the patient. CONCLUSIONS: Topical cholestyramine ointment may be a safe and efficacious treatment option for perianal irritation due to bile acids.

Antipruritics↗
PubMed1995

Longitudinal compliance with annual screening for fecal occult blood. Minnesota Colon Cancer Control Study.

In a randomized, controlled trial of fecal occult blood screening for colorectal cancer, the Minnesota Colon Cancer Control Study carried out 11 annual mail screens in two phases between 1976 and 1992. This long-term compliance record of 15,476 individuals is summarized and related to demographic characteristics as well as to the screening experience of the participants. There was a strong and consistent effect of age, with peak compliance among participants about 70 years old, and lower compliance among the youngest (< or = 55 years) and oldest (> or = 80 years) participants. There was a significantly higher rate of screen compliance among participants who lived with other participants, compared with households where only one individual participated in the study. Finally, participants who underwent a diagnostic colorectal examination with negative results had significantly lower odds of compliance.

Aged↗
PubMed1995

Homozygous deletions but no sequence mutations in coding regions of p15 or p16 in human primary bladder tumors.

Chromosome 9p21 appears to harbor a tumor suppressor gene, as evidenced by deletions in this region in a variety of human primary tumors and cell lines. To map the deletion at 9p21 in bladder tumors, we analyzed DNA from 28 tumor and normal pairs at five microsatellite markers that flank the region occupied by the putative tumor suppressor genes p16 and p15. Loss of heterozygosity (LOH) at the markers human interferon (HIFN) alpha and D9S171, which are adjacent to the p15 and p16 loci, was detected in 41% and 33%, respectively, of informative cases of bladder tumors. No sequence mutations were detected in exons 1 or 2 of either p15 or p16 in any of the bladder tumors. Three sequence-tagged site markers in the region bordered by HIFN alpha and D9S171 were used to further map the deleted region by multiplex polymerase chain reaction with the HIFN gamma maker (on chromosome 12) as a control for amplification. Six of 11 tumors with LOH at surrounding markers had homozygous deletions of the marker c5.1, which is located within the p16 gene; and two tumors appeared to have homozygous deletions within p15 (RN1.1) but not p16 (c5.1). A recently identified microsatellite marker, p16-CA-1, located 16 kb distal to p16, proved valuable in defining the minimal deletion involved in these bladder tumors. Five tumors exhibited homozygous deletions of this marker but not HIFN alpha and two tumors showed LOH at this marker and homozygous deletion of p16. Although these data could not be used to identify p16 or p15 as the definitive tumor suppressor gene in this region that is involved in bladder carcinogenesis, they suggest that homozygous deletion is a common mechanism of loss of tumor suppressor gene function in this region.

Base Sequence↗
PubMed1995

Homozygous deletions at chromosome 9p21 and mutation analysis of p16 and p15 in microdissected primary non-small cell lung cancers.

Loss of heterozygosity on chromosome 9p has been detected in many primary human tumors and cell lines, suggesting that this chromosomal arm harbors one or more tumor suppressor genes. The recently cloned p16 and p15 genes, mapped to 9p21, are likely candidates for such tumor suppressors. To map the deletion at chromosome 9p21 in non-small cell lung tumors, we analyzed DNA from 25 tumors and matching normal DNAs at six microsatellite markers that flank the region occupied by the p16 and p15 genes. Loss of heterozygosity of at least one microsatellite marker on chromosome 9p21 was detected in 13 (52%) of 25 tumors, including one tumor that exhibited homozygous deletion of both human IFNalpha and D9S171. Six tumors analyzed by a comparative multiplex PCR technique showed homozygous deletions of the sequence tag site marker c5.1 (within p16). Screening for mutations in p16 and p15 revealed one tumor with a non-sense mutation in exon 2 of p16, but no mutations were detected in p15 in any of the tumors. Thus, in these analyses approximately one-half of the non-small cell lung tumors had loss of heterozygosity at chromosome 9p21, and of these tumors, one-half had homozygous deletions of the region that includes p16. This appears to confirm the importance of a locus in this region critical to growth control in lung. The apparent lack of other mutations in p16 and p15 in the tumors with loss of heterozygosity leaves open the possibility of an unidentified gene in this region that may function as a tumor suppressor.

Adenocarcinoma↗