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Biomedical subjects

D B Smith

Publications and source records attributed to D B Smith.

At least 19 recordsLinked to original sources
PubMed1992

Computer system for assisting with clinical interpretation of tumour marker data.

OBJECTIVE: To design and evaluate a computer advisory system for the treatment of gestational trophoblastic tumour. DESIGN: A comparison of clinicians' treatment decisions with those of the computer system. Two datasets were used: one to calibrate the system and one to independently evaluate it. SETTING: Department of medical oncology. PATIENTS: Computerised records of 290 patients with low risk gestational trophoblastic tumour for whom the advisory system could predict the adequacy of treatment. The calibration set comprised patients admitted during 1979-86(227) and the test set patients during 1986-89(63). MAIN OUTCOME MEASURES: The system's accuracy in predicting need to change treatment compared with clinicians' actions. The mean time faster that the system was in predicting the need to change treatment. RESULTS: On the calibration dataset the system was 94% (164/174) accurate in predicting patients whose treatment was adequate, recommending change when none occurred in only 10 (6%) patients. In patients whose treatment was changed the system recommended change earlier than clinicians in 39/53 cases (74%), with a mean time advantage of 14.9 (SE 2.02) days. On the test dataset the system had an accuracy of 91% (31/34) in predicting treatment adequacy and a false positive rate of 9% (3/34). The system recommended change earlier than clinicians in 22/29 cases (76%), with a mean time advantage of 12.5 (2.22) days. CONCLUSIONS: The computer advisory system could improve patient management by reducing the time spent receiving ineffective treatment. This has implications for both patient time and clinical costs.

Biomarkers, Tumor↗
PubMed1992

Immunological homology among azoreductases from Clostridium and Eubacterium strains isolated from human intestinal microflora.

Azoreductases from several anaerobic intestinal bacteria have been shown to reduce azo dyes to carcinogenic aromatic amines. To evaluate the structural similarities of azoreductases from four species of Clostridium and one species of Eubacterium, a polyclonal antibody against purified Clostridium perfringens azoreductase was generated in rabbits. This antibody inhibited the azoreductase activity of all five bacteria tested. ELISA showed different degrees of binding of the antibody to various species of bacteria. In a Western blot, the antibody reacted with the purified azoreductases from all four Clostridium species and the Eubacterium species. These results demonstrate that the azoreductases from the bacteria tested share similar antigenic domains, which are probably located in the active site of the enzyme. Azoreductases from these intestinal bacteria are similar enough to be considered as a single group of enzymes with respect to their functions and antigenicity.

Blotting, Western↗
PubMed1992

Extreme heterogeneity of Ty1-copia group retrotransposons in plants.

We have used the polymerase chain reaction to analyse Ty1-copia group retrotransposons of flowering plants. All eight species studied contain reverse transcriptase fragments from Ty1-copia group retrotransposons. Sequence analysis of 31 subcloned fragments from potato reveals that each is different from the others, with predicted amino acid diversities between individual fragments varying between 5% and 75%. Such sequence heterogeneity within a single species contrasts strongly with the limited diversity seen in such retrotransposons in yeast and Drosophila. The fragments from the other seven plant species examined are also heterogeneous, both within and between species, showing that this is a general property of this transposon group in plants. Phylogenetic analysis of all these sequences reveals that many of them fall into subgroups which span species boundaries, such that the closest homologue of one sequence is often from a different species. We suggest that both vertical transmission of Ty1-copia group retrotransposons within plant lineages and horizontal transmission between different species have played roles in the evolution of Ty1-copia group retrotransposons in flowering plants.

Amino Acid Sequence↗
PubMed1992

A Ty1-copia group retrotransposon sequence in a vertebrate.

We have used the polymerase chain reaction (PCR) to isolate a sequence characteristic of a Ty1-copia group retrotransposon from the genome of the herring (Clupea harengus). This is the first Ty1-copia group retrotransposon sequence described in a vertebrate. Phylogenetic comparison of this sequence with other members of this group of retrotransposons shows that it resembles more closely some Ty1-copia group members from Drosophila melanogaster than other group members in plants and fungi. These observations provide further evidence that the Ty1-copia group LTR retrotransposons span many of the major eukaryote species boundaries, suggesting that horizontal transmission between different species has played a role in the evolution of this retrotransposon group.

Amino Acid Sequence↗
PubMed1992

Phase I trial of temozolomide (CCRG 81045: M&B 39831: NSC 362856).

Temozolomide (CCRG 81045: M&B 39831: NSC 362856) is an analogue of mitozolomide displaying similar broad spectrum activity in mouse tumours, but showing considerably less myelosuppression in the toxicology screen. Temozolomide was initially studied intravenously at doses between 50-200 mg m-2 and subsequently was given orally up to 1,200 mg m-2. A total of 51 patients were entered on the single dose schedule. Temozolomide exhibits linear pharmacokinetics with increasing dose. Myelotoxicity was dose limiting. Experimentally, temozolomide activity was schedule dependent and therefore oral administration was studied as a daily x 5 schedule between total doses of 750 and 1,200 mg m-2 in 42 patients. Myelosuppression was again dose limiting. The recommended dose for Phase II trials is 150 mg m-2 po for 5 days (total dose 750 mg m-2) for the first course, and if no major myelosuppression is detected on day 22 of the 4 week cycle, the subsequent courses can be given at 200 mg m-2 for 5 days (total dose 1 g m-2) on a 4 week cycle. Mild to moderate nausea and vomiting was dose related but readily controlled with antiemetics. Clinical activity was detected using the 5 day schedule in four (2CR, 2PR; 17%) out of 23 patients with melanoma and in one patient with mycosis fungoides (CR lasting 7 months). Two patients with recurrent high grade gliomas have also had partial responses. Temozolomide is easy to use clinically and generally well tolerated. In the extended Phase I trial temozolomide only occasionally exhibited the unpredictable myelosuppression seen with mitozolomide.

Adult↗
PubMed1992

Single agent activity of carboplatin in patients with previously untreated non-seminomatous germ cell tumours.

The response to a single course of carboplatin has been investigated in 12 patients with previously untreated non-seminomatous testicular germ cell tumours. Patients received one course of carboplatin at a dose calculated to achieve a target area under the free carboplatin plasma concentration versus time curve (AUC) of 7 mg/ml x mins using the formula: dose (mgs) = target AUC x (GFR + 25). Response to carboplatin was assessed after a single course and treatment was then continued on the POMB/ACE schedule. Ten of 12 patients had either a greater than 50% decrease in serum HCG and/or AFP levels or a greater than 50% decrease in tumour volume after a single course of carboplatin. No patient had evidence of disease progression after carboplatin. This study demonstrates that single agent carboplatin is highly active in patients with non-seminomatous testicular germ cell tumours and thus provides evidence to justify its inclusion in chemotherapy combinations.

Carboplatin↗
PubMed1992

Experimental tests of the cortical imaging technique--applications to the response to median nerve stimulation and the localization of epileptiform discharges.

In a previous paper a method for simulating the electric potentials on the surface of the brain was introduced. This method consisted of the construction of a layer of radially oriented current dipoles in a conducting sphere that simulated the head so that the voltages generated by the layer would take the values measured on the surface of the medium (the scalp). The harmonic potential function for this layer was then evaluated in the interior of the medium in an attempt to approximate the potentials that would be generated by the actual neural sources but which could not be observed without recourse to invasive recording techniques. This method, the cortical imaging technique (CIT), has been previously tested by applying it to artificially generated data where the "cortical surface" potentials were known and could be compared with CIT-generated potentials. In this paper the method is tested by applying it to the scalp-recorded potentials evoked by right median nerve stimulation, where direct cortical recordings are available for comparison, and to the scalp-recorded epileptiform discharges from two patients where the spike foci were well defined. The effects of varying the "noise ratio," an input parameter in CIT which allows one to account for noise in scalp-recorded data, is discussed.

Cerebral Cortex↗
PubMed1992

Activation of simian virus 40 transcription in vitro by T antigen.

Simian virus 40 is repressed when the viral early gene product large tumor antigen (TAg) binds to specific sites within the viral origin and DNA replication ensues. Late transcription is activated by TAg, even in the absence of viral DNA replication. We show here that TAg produced in human 293 cells can selectively activate Simian virus 40 transcription in a cell-free system. In the absence of DNA binding by TAg, early and late transcription are both activated, as they are in vivo, suggesting that the effect might be mediated by a cellular component(s) utilized by both the early and late promoters. When TAg binds to the viral origin of replication, early transcription is repressed but the late promoter activation is unaffected. Various preparations of TAg differed in their activities, with some able both to bind DNA and to activate transcription and others able to do only one or the other. Since these variations might be explained by variable amounts of associated factors that copurified with TAg, we asked whether a bacterially derived protein could regulate transcription. An NH2-terminal 272-amino-acid fragment of TAg, produced in Escherichia coli as a glutathione S-transferase fusion protein, retains the ability to activate transcription in vitro, similar to that of the full-length protein. Structural features of this region that might be important are discussed.

Amino Acid Sequence↗
PubMed1992

The effects of treatment for cancer on male fertility and sexuality.

The sequelae of some treatments for cancer, by virtue of their systemic action, adversely affect three aspects of male sexuality: desire, physical function, and cytokinetic gonadal processes. Other more localized therapies, such as surgery and radiation therapy, may affect only one aspect. Frequently, the effects of cancer therapy are interrelated, thus making it difficult to identify any single problem. This article discusses the impact of medical therapy, including chemotherapy, surgery, radiation therapy, and hormonal manipulation, as they relate to male sexuality. Interventions to promote sexual rehabilitation, either by intensive therapy or nursing actions, are discussed.

Antineoplastic Agents↗
PubMed1991

Comparison of ondansetron and ondansetron plus dexamethasone as antiemetic prophylaxis during cisplatin-containing chemotherapy.

Ondansetron, a serotonin antagonist, is effective in controlling the emesis associated with cancer chemotherapy; however, emesis in patients receiving high-dose cisplatin is poorly controlled by ondansetron alone. Dexamethasone is an effective antiemetic with no known interaction with serotonin receptors and was thus chosen for study in combination with ondansetron. 31 patients (30 male, 1 female; median age 28.5 years, range 18-49) receiving a 4-day course of a chemotherapy regimen containing cisplatin (100-120 mg/m2) for metastatic germ-cell tumours were entered in a randomised, double-blind, cross-over trial comparing oral ondansetron plus placebo with oral ondansetron plus dexamethasone as antiemetic prophylaxis. Ondansetron (8 mg every 8 h) was given to all patients for 8 days from the start of chemotherapy. Patients were given 8 mg of dexamethasone or placebo every 8 h starting 2 h before cisplatin (on day 4) and continuing for six doses (ie, for 2 days only). A second course of chemotherapy began 14 days after the start of the first, during which patients crossed over to the alternative antiemetic regimen. Results were available from 27 patients. In the 24-48 h after cisplatin 78% of patients taking ondansetron plus dexamethasone reported complete or major control of emesis compared with 30% of those taking ondansetron plus placebo (p = 0.001). Cross-over analysis showed a significant advantage for ondansetron plus dexamethasone in the control of nausea (p = 0.013) and emesis (p less than 0.001) over the 8-day study. 24 of 26 patients expressed a preference for the combination therapy (p less than 0.001). Ondansetron plus dexamethasone is effective antiemetic prophylaxis for high-dose cisplatin chemotherapy, has few side effects, and is active when given orally.

Administration, Oral↗
PubMed1991

Effect of ileal conduit on patients' activities following radical cystectomy.

Over the last twenty months, 110 patients who have undergone a radical cystectomy for bladder cancer at The University of Texas M. D. Anderson Cancer Center were surveyed to assess the effect of an ileal conduit urinary diversion on postoperative activity. Postoperatively, 47.3 percent of the patients were very active, 34.5 percent were moderately active, and 18.2 percent were sedentary. Chemotherapy and the patient's gender were found to have a statistically significant effect on postoperative activity level. Chemotherapy resulted in a decrease of very active patients from 55.6 percent to 27.9 percent and an increase in sedentary patients from 11.2 percent to 30.2 percent (P = 0.005). No difference in activity levels was seen in 73.9 percent of the nonchemotherapy patients. Fifty-one percent of the men were very active as compared with only 19.1 percent of the women, whereas 20 percent more women than men were moderately active and 13 percent more were sedentary. Our experience indicates that the ileal conduit had no significant negative effect on activity if the effects of chemotherapy are controlled: 82.6 percent of the patients not receiving chemotherapy experienced either no change or an increase in their activity.

Activities of Daily Living↗
PubMed1991

Optimum management of pineal germ cell tumours.

Non-seminomatous pineal region germ cell tumours have a poor prognosis when treated with radiation alone but little is known of the results of treatment with modern chemotherapy. Between 1983 and 1990 five pineal region germ cell tumours presented to the Charing Cross Hospital, London. All five patients received the EpPlt/OMB chemotherapy schedule with escalated dose systemic methotrexate and intra-CSF methotrexate. Two patients had had prior radiotherapy. Four patients (80%) remain well and disease-free 6 months--5 years after completing therapy. Chemotherapy is an effective modality for the treatment of pineal germ cell tumours and should be used when non-seminomatous elements are present or when the placement of ventriculo-peritoneal shunt in the presence of malignant cells in the CSF presents a risk of dissemination.

Adolescent↗
PubMed1991

A phase II study of ondansetron as antiemetic prophylaxis in patients receiving carboplatin for advanced ovarian cancer. The North Thames Ovary Group.

Thirty four patients who were receiving carboplatin 400 mg/m2 for advanced epithelial ovarian cancer were treated with ondansetron antiemetic prophylaxis. Ondansetron was given as 4 mg oral +4 mg iv 30 minutes prior to carboplatin followed by 8 mg oral tds for 5 days. Of the evaluable patients complete or major control of emesis on day one was achieved in 94% of previously untreated patients and 81% of patients refractory to conventional antiemetic therapy. For the 5 day period as a whole 88% of untreated patients and 69% of those with refractory emesis reported complete or major control of nausea and vomiting. Fifteen patients noted no side effects with mild headache (30%) and constipation (21%) the most frequent problems in the remainder. Ondansetron is effective antiemetic prophylaxis for carboplatin chemotherapy and should allow the majority of these patients to be managed on an out-patient basis.

Adult↗
PubMed1991

Multicenter long-term safety and efficacy study of vigabatrin for refractory complex partial seizures: an update.

We followed 66 patients with refractory complex partial seizures and a favorable initial response to vigabatrin for 5 to 72 (median, 43) months. Thirty-seven patients discontinued vigabatrin for the following reasons: benefit-to-risk evaluation, 8; seizure breakthrough, 6; adverse events, 6; seizure breakthrough and adverse events, 5; moved or lost, 4; no longer eligible for study, 2; non-drug-related death, 2; narcotic abuse, 1; and patient request, three. There were no clinically significant abnormalities in laboratory studies including SMA 12, complete blood count, ECG, EEG, and visual evoked response testing, and no toxicity other than reversible, dose-dependent side effects. Based on this and other long-term data, clinical trials of vigabatrin have resumed in the United States and Canada.

Aminocaproates↗
PubMed1991

Discharges against medical advice at regional acute care hospitals.

Data from 67 acute care hospitals in the Philadelphia metropolitan area indicate that there were 7,613 discharges against medical advice (AMA) in fiscal year 1987, or 1.20 percent of all discharges that year. Diagnosis-related group (DRG), type of insurance, and sex had independent effects on the rate of AMA discharges. Urban community hospitals had the highest percent of AMA discharges. Previous studies, done in teaching facilities, may have underestimated the rate of AMA discharges.

Diagnosis-Related Groups↗