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Biomedical subjects

S Watson

Publications and source records attributed to S Watson.

At least 37 records · Page 2Linked to original sources
PubMed1996

Dopaminergic transmission in the rat retina: evidence for volume transmission.

The study was designed to determine whether dopaminergic neurotransmission in the retina can operate via volume transmission. In double immunolabelling experiments, a mismatch as well as a match was demonstrated in the rat retina between tyrosine hydroxylase (TH) and dopamine (DA) immunoreactive (ir) terminals and cell bodies and dopamine D2 receptor-like ir cell bodies and processes. The match regions were located in the inner nuclear and plexiform layers (D2 ir cell bodies plus processes). The mismatch regions were located in the ganglion cell layer, the outer plexiform layer, and the outer segment of the photoreceptor layer, where very few TH ir terminals can be found in relation to the D2 like ir processes. In similar experiments analyzing D1 receptor like ir processes versus TH ir nerve terminals, mainly a mismatch in their distribution could be demonstrated, with the D1 like ir processes present in the outer plexiform layer and the outer segment where a mismatch in D2 like receptors also exists. The demonstration of a mismatch between the localization of the TH terminal plexus and the dopamine D2 and D1 receptor subtypes in the outer plexiform layer, the outer segment and the ganglion cell layer (only D2 immunoreactivity (IR)) suggests that dopamine, mainly from the inner plexiform layer, may reach the D2 and D1 mismatch receptors via diffusion in the extracellular space. After injecting dopamine into the corpus vitreum, dopamine diffuses through the retina, and strong catecholamine (CA) fluorescence appears in the entire inner plexiform layer and the entire outer plexiform layer, representing the match and mismatch DA receptor areas, respectively. The DA is probably bound to D1 and D2 receptors in both plexiform layers, since the DA receptor antagonist chlorpromazine fully blocks the appearance of the DA fluorescence, while only a partial blockade is found after haloperidol treatment which mainly blocks D2 receptors. These results indicate that the amacrine and/or interplexiform DA cells, with sparse branches in the outer plexiform layer, can operate via volume transmission in the rat retina to influence the outer plexiform layer and the outer segment, as well as other layers of the rat retina such as the ganglion cell layer.

Animals↗
PubMed1996

A hypervariable region in VP1 of chicken infectious anemia virus mediates rate of spread and cell tropism in tissue culture.

Chicken infectious anemia virus (CIAV) is a unique infectious agent with an amino acid composition that has been found to be remarkably conserved even in isolates from different parts of the world. We have characterized field isolates of CIAV which vary significantly in terms of their abilities to replicate in culture, demonstrating a biological difference between isolates. Two sublines of MDCC-MSB1 cells that differ in their abilities to support CIAV were identified. In the MSB1(S) subline the CIA-1 isolate of CIAV was found to be less cytopathogenic than the prototype Cux-1(C) isolate; the MSB1(L) subline, which supports Cux-1(C) replication, was found to be nonpermissive for CIA-1. Alignments of the VP1 sequences of previously examined isolates with those of the field isolates CIA-1 and L-028 and the culture-adapted ConnB isolate revealed a previously unreported hypervariable region spanning amino acid positions 139 to 151. Chimeras of Cux-1(C) and CIA-1 were constructed to examine the potential for this region to affect cytopathogenicity. Transfer of a 316-bp region of Cux-1(C) open reading frame 1 into CIA-1 produced a virus with a cytopathogenic profile typical of Cux-1(C), indicating that one or both of the amino acid differences at positions 139 and 144 affect the rate of replication or the spread of infection. Transfection experiments with additional chimeras indicated that the inability of CIA-1 to replicate in MSB1(L) cells is mediated by a larger region of the genome which contains the hypervariable region in addition to upstream amino acid differences. Analysis of chimeras excluding the entire region of open reading frame 1 suggested the presence of a secondary mediator in the progression of infection in culture that was localized to a region containing a single nucleotide difference which results in amino acid differences in both VP2 (V-153) and the nuclear localization signal of VP3 (C-118). Immunofluorescence assays indicated an increased cytoplasmic distribution of VP3 and a general lack of VP3-associated apoptotic bodies in infections of CIA-1 and chimeras containing V-153 or C-118, as opposed to a primarily nuclear distribution and association with well-formed apoptotic bodies in Cux-1(C)-infected cells.

Amino Acid Sequence↗
PubMed1996

Preliminary report on a phase I study of ifosfamide and vinorelbine (navelbine) in advanced non-small cell lung cancer.

Vinorelbine (Navelbine; Burroughs Wellcome Co, Research Triangle Park, NC; Pierre Fabre Medicament, Paris, France), a semisynthetic vinca alkaloid, and ifosfamide have each shown activity as a single agent and in various combination-chemotherapy regimens against non-small cell lung cancer. Vinorelbine usually has been given on a once-weekly schedule. We designed a phase I study adding escalating doses of vinorelbine on a novel schedule of 3 consecutive days to ifosfamide in a dose-intensive regimen with granulocyte colony-stimulating factor. The goals were to define the dose-limiting toxicity and maximum tolerated dose of vinorelbine and to document the toxicity profile and the overall response and survival rates observed. Eligibility criteria included histologically or cytologically documented stage IIIB or stage IV non-small cell lung cancer, measurable or evaluable disease, and no prior chemotherapy. Treatment consisted of escalating doses of vinorelbine (starting at 15 mg/m2) on days 1, 2, and 3 and ifosfamide at 2 g/m2 and decreased to 1.6 g/m2 on days 1, 2, and 3. Granulocyte colony-stimulating factor was administered subcutaneously at 5 micrograms/kg on days 5 through 11 in all patients. Cycles were repeated every 21 days. Forty-two patients were treated. The median age was 58 years (age range, 34 to 75 years); 41 patients had a performance status of 0 or 1. Dose-limiting neutropenia was observed in two of three patients at the initial dose level of ifosfamide 2 g/m2 and vinorelbine 15 mg/m2. Ifosfamide was therefore decreased to 1.6 g/m2, and vinorelbine was subsequently escalated, with a maximum administered dose of 35 mg/m2. The recommended phase II dose was ifosfamide 1.6 g/m2 on days 1, 2, and 3 with vinorelbine 30 mg/m2 on days 1, 2, and 3, given with granulocyte colony-stimulating factor support, on a 21-day cycle. At the recommended phase II dose myelosuppression remained the most common toxic effect, with grade 3 or 4 neutropenia of brief duration occurring in 20 patients. Final analysis has not yet been completed, but responses have been observed at several dose levels. The maximum tolerated dose of vinorelbine given on days 1, 2, and 3 is 30 mg/m2 when given with ifosfamide at 1.6 g/m2 on days 1, 2, and 3 and granulocyte colony-stimulating factor support. Myelosuppression is the dose-limiting toxic effect. Future analyses of the data will report the overall response and survival rates in these patients.

Adult↗
PubMed1996

Vinorelbine (Navelbine), cisplatin, and concomitant radiation therapy for advanced malignancies of the chest: a Phase I study.

Most patients with advanced solid tumors of the chest will have local and/or distant disease progression despite standard therapy. Vinorelbine (Navelbine; Burroughs Wellcome Co, Research Triangle Park, NC; Pierre Fabre Medicament, Paris, France) is a new semisynthetic vinca alkaloid with single-agent activity in lung cancer that recently also has been shown to act as a radiosensitizer in vitro. This study aims to define the maximum tolerated dose and dose-limiting toxicity when vinorelbine is given with cisplatin and concomitant radiation therapy. To date, 25 patients with advanced malignancies of the chest have been treated in a dose-escalation trial of vinorelbine administered once weekly with cisplatin (100 mg/m2 every 21 days) and concomitant thoracic radiation therapy (2 Gy/d x 30 fractions for 60 Gy). Vinorelbine was initially given at 20 and 25 mg/m2/wk. Acute dose-limiting toxicity was myelosuppression, which was seen at a vinorelbine dose of 25/mg/m2/wk, with grade 4 neutropenia in two of three patients and one treatment-related death from neutropenic sepsis. At vinorelbine 20/mg/m2/wk, no acute dose-limiting toxicity was seen, but grade 3 or 4 esophagitis developed in three of six patients near the end or after completion of radiation therapy. We subsequently decreased the administration of vinorelbine to weeks 1, 2, 4, and 5. Tolerance appears to be greater with this schedule; however, severe or life-threatening esophagitis at the completion of therapy continues to be observed. Given these preliminary results, it appears feasible to treat patients with advanced chest malignancies with concomitant cisplatin, vinorelbine, and radiation therapy. The significant dose reduction of vinorelbine that is necessary with concomitant radiation therapy provides the first in vivo evidence of a strong radiosensitizing effect of vinorelbine. The schedule is currently being modified to reduce the incidence of esophagitis.

Adult↗
PubMed1996

Cloning and characterization of multiple opioid receptors.

Over the course of 1 to 2 years, the field has moved swiftly to investigate the functional and structural properties of the newly cloned opioid receptors. Achieving a better understanding of these macromolecules is likely to have profound implications for drug design aimed at the production of better analgesic drugs, for a more fundamental understanding of mechanisms of action of drugs of abuse, and for a more comprehensive knowledge base regarding the biology of opioid peptides in particular, and neuroactive peptides in general.

Animals↗
PubMed1995

A phase I trial of concomitant chemoradiotherapy with cisplatin dose intensification and granulocyte-colony stimulating factor support for advanced malignancies of the chest.

UNLABELLED: Concomitant chemoradiotherapy with cisplatin and combination chemotherapy in the neoadjuvant setting have both shown promising results. PURPOSE: To identify a locally and systemically active concomitant chemoradiotherapy regimen incorporating high-dose cisplatin, interferon alfa-2a (IFN), fluorouracil (5-FU), hydroxyurea (HU) and radiotherapy. METHODS: Phase I cohort design establishing the maximal tolerated dose (MTD) of cisplatin with and without granulocyte colony stimulating factor (GCSF). For the first six dose levels, a 4-week cycle consisted of escalating doses of cisplatin during weeks 1 and 2, IFN (week 1), and 5-FU and HU (week 2) with single daily radiation fractions of 200 cGy during days 1-5 of weeks 1-3 and no treatment in week 4. When dose-limiting neutropenia was encountered. GCSF was added during weeks 1, 3, and 4. Finally, to decrease esophagitis, the radiotherapy schedule was altered to 150 cGy twice daily during weeks 1 and 2, followed by a 2-week break (level 7). RESULTS: Forty-nine patients with refractory chest malignancies were treated. The MTD of this regimen without GCSF was cisplatin 50 mg/m2 in weeks 1 and 2, IFN 5 million Units (MU)/m2 per day on days 1-5 in week 1, 5-FU 800 mg/m2 per day for 5 days by continuous infusion, and HU 500 mg every 12 h for 11 doses during week 2. The addition of GCSF during weeks 1, 3, and 4 allowed for escalation of cisplatin to 100 mg/m2 during weeks 1 and 2, with a decreased dose of IFN at 2.5 MU/m2 per day to avoid renal toxicity. Dose-limiting toxicity (DLT) included severe neutropenia, thrombocytopenia, and esophagitis in 5 of 13 patients. Increased thrombocytopenia in patients receiving GCSF was not observed. During hyperfractionated radiotherapy (level 7) chemotherapy doses were as above except for a reduction of 5-FU to 600 mg/m2 per day. While severe esophagitis was reduced, grade 4 thrombocytopenia became more prevalent and was seen in 6 of 7 patients. In-field tumor responses were observed in 17 of 28 evaluated patients with non-small-cell lung cancer. The median times to progression and survival were 4 and 6 months, respectively. When only patients with all known disease confined to the radiotherapy field were considered the corresponding times were 6 and 15 months, respectively. Most treatment failures occurred outside of the irradiated field. CONCLUSIONS: (1) This intensive multimodality regimen can be given with aggressive supportive care incorporating GCSF. The recommended phase II doses for a 4-week cycle are cisplatin 50 mg/m2 week 1, and 100 mg/m2 week 2, IFN 2.5 MU, HU 500 mg every 12 h x 11 and 5-FU 800 mg/m2 per day with single fraction radiotherapy during weeks 1-3 and GCSF during weeks 1, 3, and 4. (2) GCSF can be safely administered and provides effective support of neutrophils when administered simultaneously with IFN, cisplatin, and chest radiotherapy. (3) There is synergistic renal toxicity when high doses of IFN and cisplatin are given together. (4) Hyperfractionated radiotherapy decreases the severity of esophagitis but increases thrombocytopenia. (5) Although highly toxic, response rates, time to progression and survival figures with this regimen are encouraging and support its investigation in the phase II setting.

Adult↗
PubMed1995

Effects of anxiety arousal and mental stress on the vestibulo-ocular reflex.

Although the subjective reports of patients suggest that anxiety may aggravate vertigo and imbalance, there has been little research into how anxiety might directly affect balance system functioning. We conducted two studies to examine the effect of anxiety and arousal on the vestibulo-ocular reflex (VOR). In the first study, pre-lest fear ratings were obtained from 20 normal subjects and 36 anxious subjects immediately prior to rotation and caloric testing. Fear ratings were significantly correlated with the maximum slow-phase velocity (SPV) of nystagmus induced by caloric testing. In the second study, we assessed the VOR response to rotation of 36 normal subjects under 3 task conditions: a) minimal alerting (counting backwards during rotation), b) physical arousal (induced by exertion prior to rotation); c) mental arousal (induced by performance of stressful mental tasks during rotation). Both the physical and mental tasks induced a significant increase in heart rate compared with the alerting condition. The maximum SPV of the nystagmus induced by rotation was significantly greater during performance of the mental task than in the other two conditions. These combined results indicate that anxiety may influence the gain of the VOR.

Adolescent↗
PubMed1995

Outsourcing gets providers back to the basics.

Information technology is advancing so quickly that many organizations can't keep up. That's why demand for the outsourcing of data processing functions is growing as providers and payers attempt to implement the latest technology while holding costs down. Those investigating outsourcing must carefully scrutinize whether an arrangement actually will cut costs, experts advise. And clients should review contract terms to ensure all expectations are spelled out.

Contract Services↗
PubMed1995

The marriage of financial and clinical software.

As physicians feel increased pressure from managed care to operate more efficiently, they're expecting more from their practice management software than the streamlining of administrative tasks. Vendors are responding by adding clinical functions to their products.

Ambulatory Care Information Systems↗
PubMed1995

Provider automation. Focusing on the big picture.

St. Vincent's Hospital in Birmingham, Ala., is preparing for a new world of health care by creating an enterprisewide information systems strategy rather than developing automation solutions for departmental "islands."

Alabama↗