PubMed Health⌕ Search

Biomedical subjects

K Webster

Publications and source records attributed to K Webster.

At least 91 records · Page 5Linked to original sources
PubMed1996

Continuous subcutaneous administration of mesna to prevent ifosfamide-induced hemorrhagic cystitis.

Hemorrhagic cystitis is a major potential toxicity of ifosfamide that can be prevented by administering mesna along with the cytotoxic agent. Mesna is generally administered by the intravenous route, although experience with oral delivery of the drug has increased. The continuous subcutaneous administration of mesna has the advantage of not requiring intravenous access. In addition, subcutaneous delivery of the neutralizing agent will not be associated with the risk of inadequate urinary mesna concentrations, such as in a patient taking oral mesna who experiences severe ifosfamide-induced emesis and is unable to absorb the drug. Limited clinical experience with continuous subcutaneous mesna administration suggests it is a safe, practical, and economic method of drug delivery that permits ifosfamide to be administered successfully in the outpatient setting.

Administration, Oral↗
PubMed1996

Comparison between Centcor CA 125 and CA 125 II assays.

Second generation CA 125 assays are expected to replace the original CA 125 assays soon. This study compares the Centcor CA 125 II and the original Centcor CA 125 assays in 50 women: 34 with gynecologic cancers, 5 with benign conditions and 11 healthy. The serum values obtained by both assays were not statistically different and showed high correlation especially for values < 300 U/ml. Two patients who had false elevation of CA 125 by the original assay secondary to human antimouse antibody had normal values by the CA 125 II assay. It is concluded that CA 125 serum values obtained by the Centcor CA 125 II assay correlate well with the values obtained by the original Centcor CA 125 assay especially for values < 300 U/ml and are less likely to show elevated false positive results secondary to human antimouse antibody.

Adult↗
PubMed1995

Respiratory response to CO2 in the hypocapnic range in awake humans.

The response of respiratory motor output to CO2 in the hypocapnic range (< 36 Torr PCO2) in the absence of hypoxemia is not well characterized in awake normal humans. We induced hypocapnia with hyperoxia in 16 normal volunteers by placing them on a volume-cycled ventilator in the assist mode. Subjects were not aware of the purpose of the study. All subjects continued rhythmic breathing despite high tidal volumes and severe hypocapnia (approximately 25 Torr alveolar PCO2). Inspired CO2 fraction was increased in steps, and changes in respiratory motor output were quantitated from changes in airway pressure at constant volume and flow, changes in respiratory rate, and change in rate of decline in airway pressure before triggering (dP/dt). There was a significant increase in respiratory muscle pressure, but not in respiratory rate, from 26 to 36 Torr PCO2. The slope of the response increased gradually from 26 to 41 Torr PCO2. Respiratory rate significantly increased only above 36 Torr. We conclude that the response to PCO2 in the hypocapnic range is basically nonlinear with no clear CO2 threshold and the CO2 responsiveness extends well below eupneic CO2 levels.

Adult↗
PubMed1994

Management of premature rupture of membranes at term: randomized trial.

OBJECTIVE: We hypothesize that expectant management in the presence of premature rupture of membranes at term would result in a lower cesarean birth rate with no increase in maternal, fetal, or neonatal infection. STUDY DESIGN: Term patients who consented to the study were randomly allocated either to expectant management for 48 hours or to induction of labor 8 hours after premature rupture of membranes. Premature rupture of membranes was confirmed by sterile speculum examination of the vagina. Patients randomized to expectant management were transferred to antenatal care and were not examined vaginally until they went into labor. Patients randomized to induction of labor had induction with oxytocin 8 hours after premature rupture of membranes. RESULTS: Two hundred sixty-two patients were randomized to the expectant management and induction of labor groups. The cesarean birth rate and the clinical diagnosis of postpartum endometritis was not significantly different in the two groups. Pathologic diagnosis of chorioamnionitis and funisitis, however, was significantly greater in the expectant management group (p < 0.05). Eight of the 15 babies with funisitis were admitted to the neonatal intensive care unit for therapy (two in the induction of labor group and six in the expectant management group, p < 0.05). CONCLUSION: Expectant management did not reduce the incidence of cesarean birth and increased the pathologic diagnosis of funisitis and newborn requirements for neonatal intensive care.

Cesarean Section↗
PubMed1994

An approach to the study of upper airway function in humans.

Current methods for testing upper airway (UA) collapsibility in humans tend to produce intervention-related changes in some of the variables that affect UA stability. Therefore, their results may not reflect UA stability under the experimental conditions of interest. In the proposed method, the subject lies in a body enclosure with head and neck out. Pressure is altered in brief (approximately 0.2-s) pulses to avoid behavioral responses. The collapsibility of UA under "static" conditions is tested by delivering identical pressure pulses simultaneously to the airway and body surface inside the shell. Because the pressure applied to the respiratory system is not altered, cessation of flow indicates closure, and the pressure at which this happens is Pclosure. Collapsibility under dynamic conditions is tested by applying brief negative pulses to the shell only, thereby forcing an increase in inspiratory flow. Ten normal awake subjects were tested. None of the subjects developed closure when negative pulses (0 to -16 cmH2O) were applied to both airway and shell during inspiration or expiration with either nose or mouth breathing. There were only small reductions in flow, indicating minor narrowing. By contrast, pressure pulses of similar magnitude applied to the shell alone were associated with closure in 5 of 10 subjects. We conclude that the UA of normal awake humans is fairly stable under the influence of statistically applied pressure but susceptible to collapse under conditions of increased flow. Pclosure determined under static conditions underestimates the vulnerability of the UA to collapse under dynamic conditions.

Adult↗
PubMed1993

Are intraligamentary injections intravascular?

A pressure type syringe was used to give intraligamentary injections (IL) to upper teeth of two formulations commonly used in general practice, lignocaine and prilocaine. Assay of plasma levels of drug was carried out by high performance liquid chromatography. Results of assays after intraligamentary injections were then compared with results of assays after intravenous injections of plain drug in the same subjects. Both formulations of local anaesthetic were found as peak levels in the circulation, presumably after intraosseous spread, by 2 minutes following the intraligamentary injections. For lignocaine the peak amount was nearly 7% of the intravenous dose and for prilocaine the peak amount was 25% of the intravenous dose, at 2 minutes after injection. It was concluded that IL injections for healthy adults were unlikely to cause systemic unwanted effects when given in small doses.

Adult↗
PubMed1993

Isoenzyme variation within the genus Cryptosporidium.

Soluble extracts of the oocysts of Cryptosporidium parvum had demonstrable, but low, activities of malate dehydrogenase (MDH, EC. 1.1.1.37), carboxylesterase (ES, EC 3.1.1.1) and lactate dehydrogenase (LDH, EC. 1.1.1.27) following thin-layer starch-gel electrophoresis. Much higher activities of glucose phosphate isomerase (GPI, EC. 5.3.1.9) and phosphoglucomutase (PGM, EC. 2.7.5.1) were found, and zymograms of these two enzymes were used to characterise isolates of C. parvum from human, bovine, ovine and cervine sources, C. muris from the brown rat and C. baileyi from young turkeys. PGM and GPI zymograms clearly distinguished between C. parvum, C. muris and C. baileyi. The five isolates of C. parvum showed the same electrophoretic mobility for GPI, whereas the PGM mobility of the single human isolate of C. parvum examined was clearly different from that of the other isolates. This is the first report of the use of isoenzymes to distinguish between species and isolates of Cryptosporidium.

Animals↗
PubMed1993

Malignant mixed mullerian tumors of the ovary. An analysis of two long-term survivors.

Long-term survival following the diagnosis of ovarian malignant mixed mullerian tumor (MMMT) is unusual. This report analyzes two such long-term survivors. One patient presented with a FIGO Stage III, homologous MMMT treated initially with a combination of surgery and chemotherapy. Residual disease, present at the time of initial operation, responded to the chemotherapy; however, the tumor recurred 2 1/2 years postoperatively. This recurrence responded to a combination of surgery and chemotherapy, including continuous adjuvant chemotherapy. This patient is alive, on maintenance chemotherapy, and without evidence of disease, approximately 7 years after the recurrence and 9 years after the initial presentation. The other patient presented with a FIGO Stage III heterologous MMMT treated initially with combined surgery and chemotherapy. Residual disease was present at the time of initial operation. Persistent pelvic disease led to exploratory laparotomy, excision of an 8-cm diameter pelvic mass, and postoperative radiation therapy. The tumor recurred in the left supraclavicular lymph nodes 2 years later (3 years after the initial presentation). This recurrence responded to radiation therapy. This patient was last seen 2 years later (5 years after the initial presentation). At that time, she was without evidence of recurrence. She died 7 1/2 years after her initial presentation. These two patients represent examples of the unusual occurrence of patients with advanced-stage ovarian MMMT experiencing long-term survival following surgical and adjuvant therapy.

Aged↗
PubMed1992

Randomised trial of artesunate and mefloquine alone and in sequence for acute uncomplicated falciparum malaria.

The increasing frequency of therapeutic failures in falciparum malaria in Thailand shows an urgent need for effective drugs or drug combinations. Artesunate, a qinghaosu derivative, is effective in clearing parasitaemia rapidly, but the recrudescence rate can be as high as 50%. We have compared artesunate followed by mefloquine with each drug alone in acute, uncomplicated falciparum malaria. 127 patients were randomly assigned treatment with artesunate (600 mg over 5 days), mefloquine (750 mg then 500 mg 6 h later), or artesunate followed by mefloquine. All patients were admitted to hospital for 28 days to exclude reinfection. Cure was defined as no recrudescence during the 28 days' follow-up. The cure rates for mefloquine and artesunate alone were 81% (30/37 patients) and 88% (35/40); the combination was effective in all of 39 patients. Fever and parasite clearance times were significantly shorter in the groups that received artesunate than in the mefloquine-only group. The frequency of nausea and vomiting was slightly, but not significantly, higher among patients who received both drugs than in the other groups. The combination of artesunate followed by mefloquine is highly effective and well tolerated in patients with acute, uncomplicated falciparum malaria in Thailand.

Acute Disease↗
PubMed1992

Echinomycin (NSC 526417) in recurrent and metastatic nonsquamous cell carcinoma of the cervix. A phase II trial of the Gynecologic Oncology Group.

Eighteen evaluable patients with recurrent or metastatic nonsquamous carcinoma of the uterine cervix were treated with 1,500 micrograms/m2 of echinomycin every 4 weeks. Seven patients had received prior chemotherapy. There was one complete response (5.6%), 95% confidence interval for response of 0-27%. The major toxicity was nausea and vomiting, which was moderate to severe in eight patients. Myelosuppression was minimal. Echinomycin in this dose and schedule displays minimal activity in patients with advanced nonsquamous carcinoma of the cervix.

Adenocarcinoma↗
PubMed1992

A primate model for human cerebral malaria: Plasmodium coatneyi-infected rhesus monkeys.

A major factor in the pathogenesis of human cerebral malaria is blockage of cerebral microvessels by the sequestration of parasitized human red blood cells (PRBC). In vitro studies indicate that sequestration of PRBC in the microvessels is mediated by the attachment of knobs on PRBC to receptors on the endothelial cell surface such as CD36, thrombospondin (TSP), and intercellular adhesion molecule-1 (ICAM-1). However, it is difficult to test this theory in vivo because fresh human brain tissues from cerebral malarial autopsy cases are not easy to obtain. Although several animal models for human cerebral malaria have been proposed, none have shown pathologic findings that are similar to those seen in humans. In order to develop an animal model for human cerebral malaria, we studied brains of rhesus monkeys infected with the primate malaria parasite, Plasmodium coatneyi. Our study demonstrated PRBC sequestration and cytoadherence of knobs on PRBC to endothelial cells in the cerebral microvessels of these monkeys. Cerebral microvessels with sequestered PRBC were shown by immunohistochemical analysis to possess CD36, TSP, and ICAM-1. These proteins were not evident in the cerebral microvessels of uninfected control monkeys. Thus, our study indicates, for the first time, that rhesus monkeys infected with P. coatneyi can be used as a primate model to study human cerebral malaria. By using this animal model, we may be able to evaluate strategies for the development of vaccines to prevent human cerebral malaria.

Animals↗
PubMed1990

Clonal growth requirements of human bladder tumor cell lines.

We have serially investigated the role of nutrients and growth factors for their ability to support the clonal growth of human bladder tumor cell lines. Five established human bladder tumor cell lines were selected for study of their requirements for clonogenic growth in semisolid cultures. We identified an "optimal medium" to be Alpha MEM medium, 15% horse serum, five micrograms/ml. of transferrin, five micrograms/ml. of insulin and 30 ng./ml. of epidermal growth factor. The "optimal assay" enhanced the growth of human bladder tumor cell lines 2.5 times compared to the standard clonogenic assay. The resulting medium is less complicated to maintain, less expensive and supports the growth of human bladder tumor cell lines better than the standard clonogenic assay.

Cell Line↗
PubMed1989

T cells from patients successfully treated with OKT3 do not react with the T-cell receptor antibody.

The mechanism of OKT3 therapy is complex and may include depletion of circulating CD3 cells, modulation of the CD3 molecule, and/or functional inactivation of T cells. Although the absolute number of circulating CD3 cells in OKT3-treated patients is used to monitor therapy, many laboratories assign CD3 numbers based on reactivity with OKT3. These CD3 numbers could be artificially low since the epitope recognized by OKT3 may already be occupied. Using a monoclonal antibody against a different CD3 epitope, we detected CD3 expression on T lymphocytes from 18/18 OKT3-treated patients. Nonetheless, OKT3 therapy in these patients was clinically successful, suggesting that monitoring patients solely for CD3 is uninformative. Since CD3 is associated with the T-cell receptor (TcR), we also evaluated alpha-TcR-1, a monoclonal antibody which detects a conformational determinant of the CD3/TcR alpha/beta complex, and found that less than 1% of the CD3 cells from OKT3-treated patients reacted. Furthermore, these cells were unresponsive to allogeneic stimulation. However, when patient cells were cultured overnight in the absence of OKT3, both alpha-TcR 1 binding and responsiveness to allogeneic stimulation became detectable. Thus, the monitoring of patients treated with OKT3 can be more informative if lymphocytes are tested for reactivity with alpha-TcR-1 and an alpha-CD3 antibody other than OKT3.

Antibodies, Monoclonal↗
PubMed1988

Graves' disease of the beta cell: glucose dysregulation due to islet-cell stimulating antibodies.

The immunoglobulin fractions of serum from patients with spontaneous hyperinsulinaemic hypoglycaemia and others with type 1 diabetes stimulated insulin release both in islet-cell cultures and in vivo in rats. Serum from patients with type 2 diabetes, which is not an autoimmune disease, did not stimulate insulin release. The discovery of islet-cell-stimulating antibodies (ICSTA) completes for the islet the triad of autoantibodies (anticytoplasmic, antiproduct, and antireceptor) previously described in autoimmune thyroid disease. ICSTA may be important modulators of islet-cell secretion in man.

Adolescent↗