Increasing response rates from physicians in oncology research: a structured literature review and data from a recent physician survey

Although the physician survey has become an important tool for oncology-focused health services research, such surveys often achieve low response rates. This mini-review reports the results of a structured review of the literature relating to increasing response rates for physician surveys, as well as our own experience from a survey of physicians as to their referral practices for suspected haematologic malignancy in the United States. PubMed and PsychINFO databases were used to identify methodological articles assessing factors that influence response rates for physician surveys; the results were tabulated and reviewed for trends. We also analysed the impact of a follow-up telephone call by a physician investigator to initial non-responders in our own mailed physician survey, comparing the characteristics of those who responded before vs after the call. The systematic review suggested that monetary incentives and paper (vs web or email) surveys increase response rates. In our own survey, follow-up telephone calls increased the response rate from 43.7% to 70.5%, with little discernible difference in the characteristics of early vs later responders. We conclude that in addition to monetary incentives and paper surveys, physician-to-physician follow-up telephone calls are an effective method to increase response rates in oncology-focused physician surveys.

Limits to research risks

Risk-benefit assessment is a routine requirement for research ethics committees that review and oversee biomedical research with human subjects. Nevertheless, it remains unclear how to weigh and balance risks to research participants against the social benefits that flow from generating biomedical knowledge. In this article, we address the question of whether there are any reasonable criteria for defining the limit of permissible risks to individuals who provide informed consent for research participation. We argue against any a priori limit to permissible research risks. However, attention to the uncertainty of potential social benefit that can be derived from any particular study warrants caution in exposing prospective research participants to a substantial likelihood of serious harm.

Diagnosis of cystic fibrosis in the Republic of Ireland: epidemiology and costs

There were four objectives in this study: (1) determine the incidence of cystic fibrosis (CF) in Ireland; (2) estimate the cost of diagnosing CF; (3) clarify the characteristics and outcomes of the nationwide diagnostic efforts and (4) identify disparities. Surveys were conducted to determine the number, methods, costs and outcomes for sweat tests in Ireland from 2001 through 2003. The results allowed us to determine that Ireland's CF incidence is the world's highest at 1:1353. The average cost for diagnosis was Euro 2663 per patient. Analyses of data in The Cystic Fibrosis Registry of Ireland revealed longer delays when diagnosis followed respiratory symptoms, rather than gastrointestinal signs, and also in girls compared to boys, particularly those presenting with respiratory symptoms. Although expenditures for diagnosing of CF in Ireland are relatively modest, the high incidence and age of diagnosis, as well as gender-related disparities, are sufficient to warrant investment in national newborn screening.

Entering a Clinical Trial: Is It Right For You?–A randomized study of the Clinical Trials Video and its impact on the informed consent process

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Background: In an effort to improve the informed consent process for subjects considering participation in a clinical trial, we created an educational video: “Entering a Clinical Trial: Is it Right for You?” In this randomized study, we assessed the effect of the video on patients’ understanding and perceptions of clinical trials. We also assessed patient satisfaction with the video and how the video impacted decision-making and patient-provider communication. Methods: We recruited 90 adults considering cancer clinical trials of whom 77 participated. After discussing the trial with the physician and reading the trial consent form, patients were randomized to receive (n=38) or not receive (n=39) the study video. Using a validated questionnaire, we interviewed subjects to assess objective understanding of the trial, our primary endpoint, and self-reported understanding of clinical trials. All subjects completed a second interview assessing secondary endpoints, including patient-provider communication, satisfaction with video, and decision-making. We used linear regression (two-sided tests) to conduct the primary analysis and the Wilcoxon rank-sum test and descriptive statistics to analyze the secondary aims. Results: Neither objective nor self-reported understanding of clinical trials differed between the two groups (Mean 86.5 vs. 87, p=0.75). 85% (61/72) indicated the video was an important source of information about clinical trials; 89% of those who watched the video with their family/friends (n=37) said the video helped loved ones better understand clinical trials; 73% indicated it helped their family accept their decision about participation. 81% (58/72) felt better prepared to discuss the trial with their physician after watching the video. Of those who found the video helpful with decision- making, 80% (21/26) were considering a trial for the first time compared with 19% (5/26) veterans who had previously participated in a clinical trial. Conclusions: The video did not measurably improve subjects’ understanding of their clinical trials. However, subjects reported that the video was an important source of information, helped them educate their families, and enhanced patient-provider communication.

No significant financial relationships to disclose.

Preferences for and expectations about experimental therapy among participants in randomized trials

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Background: Equipoise is often viewed as the ethical precondition for randomized controlled trials (RCTs). Equipoise is usually defined as a state of uncertainty or disagreement among expert clinicians, but some ethicists argue instead that individual participants should be indifferent between the study arms. The degree to which cancer RCT participants have preferences for either arm is not known. Methods: Adults who had enrolled in a 2-arm RCT at a Dana-Farber/Harvard Cancer Center institution within 21 days were eligible. A mailed questionnaire asked about treatment assignment, treatment preference, and expectations about the relative efficacy and toxicity of the 2 arms. The primary analysis was a goodness-of-fit chi-square test of the null hypothesis that equal proportions of respondents would prefer the standard vs. investigational arm. Results: 82 of 126 RCT participants (65%) responded. 31 (38%) were assigned to the standard arm, 26 (32%) were assigned to the experimental arm, and 25 (30%) were enrolled in blinded trials. Respondents tended to prefer assignment to the experimental rather than the standard arm (p = 0.006), and expected the investigational arm to be more effective than the standard arm (p = 0.0004). Respondents did not consistently expect that either arm would be more toxic ( Table ). Conclusions: Cancer RCT participants tend to prefer the experimental arm. Thus either the design of cancer RCTs must be altered to accommodate participant preference, or individual-participant equipoise must be abandoned.

[Table: see text]

No significant financial relationships to disclose.

Use of experimental therapy outside of clinical trials among U.S. oncologists

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Background: Investigational cancer therapies being tested in clinical trials may be available outside of trials, or “off-protocol” (OPRx). There are no published data on either the frequency of OPRx or the attitudes of physicians towards OPRx. Methods: In spring 2005, we surveyed a random sample of American medical oncologists chosen from the ASCO directory regarding their attitudes and practices surrounding OPRx. We evaluated the correlation between demographic factors, attitudes, use of OPRx, and response to hypothetical cases. All statistical tests were two-sided. Results: 146 of 471 (31%) oncologists responded. 93% reported ever discussing OPRx and 81% ever prescribing OPRx. 66% reported prescribing OPRx ≥ once/year and 12% ≥ once/month. 68% reported denying requests for OPRx ≥ once/year and 6% ≥ once/month. Academic oncologists were simultaneously more likely than community oncologists to have ever provided OPRx (89% v. 75%, p = 0.06 by Fisher’s exact test), to discuss OPRx ≥ 1 month (45% v. 12%, p = .003), and to deny requests for OPRx ≥ 1 month (15% v. 2%, p = 0.02). While 61% of oncologists believe that patients should be discouraged from OPRx, only 31% felt it should not be available. 53% felt that patients considering trial enrollment should be informed if OPRx is available, whereas 34% disagreed. 26% felt that patients considering enrollment have a right to OPRx, whereas 56% disagreed. Neither practice setting nor other demographic factors predicted attitudes towards OPRx. For hypothetical cases, there was little consensus regarding when to prescribe OPRx. For example, prior to the release of data from recent trials, 41% reported that they would prescribe adjuvant trastuzumab OPRx at a patient’s request. Factors correlating with willingness to provide OPRx included non-academic practice setting (p = 0.04), > 15 years in practice (p = 0.08), belief that non-trial care and trial care are equivalent (p = 0.01) and belief that patients have a right to OPRx (p = 0.004). Conclusion: American oncologists commonly discuss and provide OPRx. Attitudes towards and utilization of OPRx vary substantially in the oncology community. Further discussion of OPRx and guideline development appear warranted.

No significant financial relationships to disclose.

What do patients value in their hospital care? An empirical perspective on autonomy centred bioethics

OBJECTIVE

Contemporary ethical accounts of the patient-provider relationship emphasise respect for patient autonomy and shared decision making. We sought to examine the relative influence of involvement in decisions, confidence and trust in providers, and treatment with respect and dignity on patients' evaluations of their hospital care.

DESIGN

Cross-sectional survey.

SETTING

Fifty one hospitals in Massachusetts.

PARTICIPANTS

Stratified random sample of adults (N=27 414) discharged from a medical, surgical, or maternity hospitalisation between January and March, 1998. Twelve thousand six hundred and eighty survey recipients responded.

MAIN OUTCOME MEASURE

Respondent would definitely be willing to recommend the hospital to family and friends.

RESULTS

In a logistic regression analysis, treatment with respect and dignity (odds ratio (OR) 3.4, 99% confidence interval (CI) 2.8 to 4.2) and confidence and trust in providers (OR 2.5, CI 2.1 to 3.0) were more strongly associated with willingness to recommend than having enough involvement in decisions (OR 1.4, CI 1.1 to 1.6). Courtesy and availability of staff (OR 2.5, CI 2.1 to 3.1), continuity and transition (OR 1.9, CI 1.5 to 2.2), attention to physical comfort (OR 1.8, CI 1.5 to 2.2), and coordination of care (OR 1.5, CI 1.3 to 1.8) were also significantly associated with willingness to recommend.

CONCLUSIONS

Confidence and trust in providers and treatment with respect and dignity are more closely associated with patients' overall evaluations of their hospitals than adequate involvement in decisions. These findings challenge a narrow emphasis on patient autonomy and shared decision making, while arguing for increased attention to trust and respect in ethical models of health care.

Quality of informed consent in cancer clinical trials: a cross-sectional survey

BACKGROUND

Investigators have to obtain informed consent before enrolling participants in clinical trials. We wanted to measure the quality of understanding among participants in clinical trials of cancer therapies, to identify correlates of increased understanding, and to assess providers' beliefs about clinical research. We also sought evidence of therapeutic misconceptions in participants and providers.

METHODS

We sent a standard questionnaire to 287 adult patients with cancer who had recently enrolled in a clinical trial at one of three affiliated institutions, and surveyed the provider who obtained each patient's consent.

FINDINGS

207 of 287 (72%) patients responded. 90% (186) of these respondents were satisfied with the informed consent process and most considered themselves to be well informed. Nevertheless, many did not recognise non-standard treatment (74%), the potential for incremental risk from participation (63%), the unproven nature of the treatment (70%), the uncertainty of benefits to self (29%), or that trials are done mainly to benefit future patients (25%). In multivariate analysis, increased knowledge was associated with college education, speaking only English at home, use of the US National Cancer Institute consent form template, not signing the consent form at initial discussion, presence of a nurse, and careful reading of the consent form. Only 28 of 61 providers (46%) recognised that the main reason for clinical trials is benefit to future patients.

INTERPRETATION

Misconceptions about cancer clinical trials are frequent among trial participants, and physician/investigators might share some of these misconceptions. Efforts to educate providers and participants about the underlying goals of clinical trials are needed.

Inflammatory bowel disease associated with immune thrombocytopenic purpura in children

OBJECTIVE

Previous reports suggest an association between inflammatory bowel disease (IBD) and immune thrombocytopenic purpura (ITP) in adults. To date, only five children with both diseases have been described. The aim of the study was to describe the characteristics of children with IBD and ITP.

METHODS

Cases were obtained from the pediatric gastroenterology community by means of the pediatric gastroenterology internet bulletin board in June 1999. Eight cases were submitted from seven medical centers. Medical records were reviewed by two pediatric gastroenterologists and a pediatric hematologist.

RESULTS

The age range of the patients was 2.1 to 16.5 years, with a mean age of 9.6 +/- 5.2 years. Four children had ulcerative colitis, three had Crohn disease, and one had indeterminate colitis. All had colonic involvement of IBD. Of eight patients, three had IBD first, three had ITP first, and two had both simultaneously. At ITP diagnosis, platelet count was less than 10,000/mL in five children, 17,000/mL in one child, and 50,000 to 60,000/mL in two children. Of the three children diagnosed with ITP first, two initially had rectal bleeding at the time of ITP diagnosis. Bone marrow evaluations, performed in six of eight children, were consistent with ITP. Six of the eight children had chronic ITP, including three children who were 5 years of age or younger. Therapy for ITP included steroids (n = 6), intravenous immunoglobulin (n = 6), Rh o (D) intravenous immunoglobulin (n = 2), and splenectomy (n = 1).

CONCLUSIONS

The authors describe the largest pediatric case series of children with IBD and ITP. More than 50% of the children had the chronic form of ITP. Most patients responded to conventional therapy for ITP and IBD.

Quality of informed consent: a new measure of understanding among research subjects

BACKGROUND

The informed consent of participants is ethically and legally required for most research involving human subjects. However, standardized methods for assessing the adequacy of informed consent to research are lacking.

METHODS AND RESULTS

We designed a brief questionnaire, the Quality of Informed Consent (QuIC), to measure subjects' actual (objective) and perceived (subjective) understanding of cancer clinical trials. The QuIC incorporates the basic elements of informed consent specified in federal regulations, assesses the therapeutic misconception (the belief that all aspects of a clinical trial are designed to directly benefit the subject), and employs the language and structure of the new National Cancer Institute template for informed consent documents. We modified the QuIC after receiving feedback from pilot tests with cancer research subjects, as well as validation from two independent expert panels. We then sent the QuIC to 287 adult cancer patients enrolled on phase I, II, or III clinical trials. Two hundred seven subjects (72%) completed the QuIC. To assess test-retest reliability, a random sample of 32 respondents was selected, of whom 17 (53%) completed the questionnaire a second time. The test-retest reliability was good with intraclass correlation coefficients of.66 for tests of objective understanding and.77 for tests of subjective understanding. The current version of the QuIC, which consists of 20 questions for objective understanding and 14 questions for subjective understanding, was tested for time and ease of administration in a sample of nine adult cancer patients. The QuIC required an average of 7.2 minutes to complete.

CONCLUSIONS

The QuIC is a brief, reliable, and valid questionnaire that holds promise as a standardized way to assess the outcome of the informed consent process in cancer clinical trials.

Rehospitalization for respiratory syncytial virus among premature infants

OBJECTIVES

New interventions to prevent respiratory syncytial virus (RSV) have recently become available. Clinical decisions about the use of these interventions require a better understanding of the incidence of and risk factors for RSV. We sought to characterize the epidemiology of severe RSV disease among premature infants and to identify high-risk subgroups.

DESIGN

Retrospective cohort.

SETTING

Kaiser Permanente Northern California, July 1992 to April 1996.

PARTICIPANTS

One thousand seven hundred twenty-one premature infants born at 23 to 36 weeks who were discharged from a neonatal intensive care nursery (NICU) within 12 months before the December to March RSV season. A secondary analysis included 769 infants discharged during the RSV season.

OUTCOME MEASURES

Hospitalization for RSV.

RESULTS

Of 1721 infants already home from the NICU at the start of the season, 3.2% were rehospitalized for RSV. In a multivariate model, risk factors for RSV hospitalization included gestation </=32 weeks (odds ratio [OR], 2.6), >/=28 days of perinatal oxygen (OR, 3.7), and NICU discharge during September to November (OR, 2.7). Predicted risk of hospitalization varied by subgroup, ranging from 1.2% to 24.6%. Among 769 infants discharged from the NICU during the RSV season, 3.5% were rehospitalized for RSV during the same season; gestation and perinatal oxygen were not associated with admission.

CONCLUSIONS

Most premature infants in this population were at less risk of severe RSV disease than previous studies in other populations have suggested. Preterm infants with a lower gestational age, a prolonged perinatal oxygen requirement, and NICU discharge within 3 months of the RSV season were most likely to require hospitalization for RSV disease. Cost-effectiveness analyses are needed to help define the role of available prophylactic interventions.

Cost-effectiveness of respiratory syncytial virus prophylaxis among preterm infants

OBJECTIVES

To evaluate the costs and benefits of two new agents, respiratory syncytial virus immune globulin (RSVIG) and palivizumab, to prevent respiratory syncytial virus (RSV) infection among premature infants discharged from the neonatal intensive care unit (NICU) before the start of the RSV season. Method. Decision analysis was used to compare the projected societal cost-effectiveness of three strategies-RSVIG, palivizumab, and no prophylaxis-among a hypothetical cohort of premature infants. Probabilities and costs of hospitalization were derived from a cohort of 1721 premature infants discharged from six Kaiser Permanente-Northern California NICUs. Efficacies of prophylaxis were based on published trials. Costs of prophylaxis were derived from published sources. Mortality among infants hospitalized for RSV was assumed to be 1.2%. Future benefits were discounted at 3%.

RESULTS

Palivizumab was both more effective and less costly than RSVIG. Cost-effectiveness varied widely by subgroup. Palivizumab appeared most cost-effective for infants whose gestational age was </=32 weeks, who required >/=28 days of oxygen in the NICU, and who were discharged from the NICU from September through November. In this subgroup, palivizumab was predicted to cost $12,000 per hospitalization averted (after taking into account savings from prevention of RSV admissions) or $33,000 per life-year saved, and the number needed to treat to avoid one hospitalization was estimated at 7.4. However, for all other subgroups, ratios ranged from $39,000 to $420,000 per hospitalization averted or $110,000 to $1,200,000 per life-year saved, and the number needed to treat extended from 15 to 152. The results were sensitive to varying assumptions about the cost and efficacy of prophylaxis, as well as the probability of hospitalization, but were less sensitive to the cost of hospitalization.

CONCLUSION

In our model, the cost of prophylaxis against RSV for most subgroups of preterm infants was high relative to the benefits realized. Lower costs might permit the benefits of prophylaxis to be extended to additional groups of preterm infants.

Rehospitalization in the first two weeks after discharge from the neonatal intensive care unit

BACKGROUND

High-risk newborns are known to have higher than average utilization of services after discharge from the neonatal intensive care unit (NICU). Most studies on this subject report aggregate data over periods ranging from 1 to 3 years postdischarge. Little is known about events that are temporally close to NICU discharge.

OBJECTIVES

To characterize rehospitalizations within the first 2 weeks after discharge from six community NICUs.

METHODS

We scanned electronic databases and reviewed the charts of rehospitalized infants from six NICUs in the Kaiser Permanente Medical Care Program. We subdivided infants into five groups based on gestational age (GA) and birth hospitalization length of stay (LOS): 1) >/=37 weeks' GA with <4 days LOS (n = 2593); 2) >/=37 weeks' GA with >/=4 days' LOS (n = 1133); 3) from 33 to 36 weeks' GA with <4 days' LOS (n = 545); 4) from 33 to 36 weeks' GA with >/=4 days' LOS (n = 1196); and 5) <33 weeks' GA (n = 587). We performed bivariate and multivariate analyses to identify predictors that might be useful for practitioners.

RESULTS

There were 6054 newborns discharged alive from the six study NICUs between August 1, 1992 and December 31, 1995, and 99.5% of these infants remained in the health plan during the 2 weeks after NICU discharge. The overall rehospitalization rate was 2.72%, which is 20% higher than the rate among healthy term newborns in the Kaiser Permanente Medical Care Program (2.26%). The two most common reasons for rehospitalization were jaundice (62/165, 37.6%) and feeding difficulties (25/165, 15.2%). Infants with 33 to 36 weeks' GA and <4 days' LOS were rehospitalized at a significantly higher rate than were all other infants (5.69%); 71% of infants in this group were rehospitalized for jaundice. The following variables predicted rehospitalization in multivariate models: <33 weeks' GA (adjusted OR [AOR]: 1.88; 95% CI: 1.10-3.21), from 33 to 36 weeks' GA with <96 hours' LOS (AOR: 2.94; 95% CI: 1.87-4.62), and birth at facility B, which had the highest rehospitalization rate of the six facilities (AOR: 1.92; 95% CI: 1.39-2.65).

CONCLUSIONS

The rate of rehospitalization among NICU graduates is higher than among healthy term infants. Most of the rehospitalizations among infants with from 33 to 36 weeks' GA and <4 days' LOS are for illnesses that are not life-threatening. Collaborative studies and new process and outcomes measures are needed to assess the effectiveness of follow-up strategies in high-risk newborns.

Physiological insulin action is opposed by beta-adrenergic mechanisms in dogs

To investigate the possible role of adrenergic mechanisms in modulating glucose homeostasis during physiological insulin changes, we studied the effects of alpha-, beta-, or combined alpha- and beta-adrenergic blockade on glucose production (Ra) and utilization (Rd) via isotope ([3-(3)H]glucose) dilution during nonstressful, nonhypoglycemic conditions in response to physiological insulin changes in conscious dogs. Without adrenergic blockade, infusion of insulin at 0.275 mU.kg-1.min-1 (control) caused glucose to fall from 92 +/- 4 to 82 +/- 4 mg/dl over 30 min, because of transient fall in Ra from 2.8 +/- 0.4 to 2.3 +/- 0.3 mg.kg-1.min-1, which recovered to base line by 30 min. There was a later rise in Rd to 3.9 +/- 0.4 mg.kg-1.min-1 at 45 min, but no counter-regulatory hormonal changes (glucagon, cortisol, epinephrine, and norepinephrine) to account for these findings in glucose kinetics. alpha-Blockade alone led to an initial rise in base-line insulin and consequent fall in glucose, associated with a transient fall in Ra but no change in Rd; infusion of insulin led to a further small fall in glucose, with no change in Ra, but with a rise at 30 min in Rd similar to controls. beta-Blockade alone led to an initial fall in insulin and modest rise in glucose; insulin infusion led to a greater rate of fall in glucose than in controls (from 112 +/- 6 to 78 +/- 7 mg/dl over 30 min).(ABSTRACT TRUNCATED AT 250 WORDS)

The regulation of basal pancreatic polypeptide levels in dogs

In response to various stimuli, pancreatic polypeptide (PP) release is predominantly mediated by cholinergic mechanisms, and may be modulated by sympathetic and opiate (inhibitory) effects. However, the mechanisms regulating basal PP levels remain unclear. We examined the possible role of the sympathetic nervous system and endogenous opiates in the regulation of basal levels of pancreatic polypeptide in trained conscious dogs. During prolonged (150 min) alpha- or beta-adrenergic blockade with phentolamine and propranolol, separately or in combination, there was no change in the basal PP levels of 154 +/- 20 pg/ml. Effective adrenergic modulation of pancreatic hormones was evident since alpha blockade led to a rise in insulin and glucagon, beta blockade led to a fall in insulin and glucagon, while combined alpha- and beta-adrenergic blockade did not affect insulin or glucagon. Opiate blockade with naloxone (1.25 mg followed by 1 microgram/kg/min) led to a delayed fall in PP from 153 +/- 22 to 89 +/- 15 pg/ml at 90 min (no change by 30 min), without a change of insulin or glucagon. Infusion of a potent morphine analogue D-Met2-Pro5-enkephalinamide (0.5 microgram/kg/min) led to a sustained fall in PP to 91 +/- 8 pg/ml by 30 min without a change in insulin or glucagon. Somatostatin infusion (0.2 microgram/kg/min) with insulin and glucagon replacement, led to a similar sustained fall in PP. It is concluded that in dogs: in contrast to insulin and glucagon, at basal conditions the plasma level of PP is not modulated by endogenous alpha- or beta-adrenergic influences.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in glucagon do not play an essential role in the glucoregulatory responses to mild hyperinsulinemia in dogs

To examine whether an increase in the glucagon concentration is essential for restoring hepatic glucose output following moderate decrements in blood glucose, we used isotope dilution techniques in trained conscious dogs (n = 5) to measure glucose production (Ra) and glucose utilization (Rd) during mild hyperinsulinemia (19 +/- 1 mU/l). In Study A, when insulin was infused to raise plasma insulin (IRI) from 13 +/- 2 to 19 +/- 1 mU/l, basal glucose (93 +/- 3 mg/dl) fell at a rate of 0.37 +/- 0.06 mg/dl/min over 30 min. Ra fell from 2.8 +/- 0.4 mg/kg/min by 0.5 +/- 0.1 mg/kg/min at 20 min (P less than 0.05), but recovered to baseline by 30 min; glucagon (IRG) fell transiently but returned to baseline by 45 min. In Study B, endogenous secretion of IRI and IRG was suppressed by infusion of somatostatin (0.2 microgram/kg/min), while peripheral concentrations were maintained constant by replacing glucagon (0.65 ng/kg/min) and insulin (0.225 mU/kg/min). Steady-state baseline plasma IRI, IRG, glucose and glucose turnover rates were similar to Study A; hyperinsulinemia was then induced as in Study A. Glucose fell by 0.78 +/- 0.19 mg/dl/min over 30 min and, as in Study A, Ra decreased transiently, but recovered to baseline by 30 min. The restoration of Ra occurred in study B despite constant IRG, and preceded later increments in cortisol and catecholamines at 60-90 min. Thus, in both studies A and B, Ra recovered to baseline without an increase in IRG and before the onset of significant hypoglycemia (glucose 83 +/- 1 and 70 +/- 1 mg/dl).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of electrocautery, CO2 laser, and contact Nd:YAG laser scalpel on the healing of intestinal incision

Leakage after intestinal resection is a serious complication with a high mortality rate. A recent study claims that cutting the intestine with the CO2 laser improves the healing of intestinal anastomoses (Ferulano et al: Eur Surg Res 16:127-130, 1984). The present study was undertaken to analyze the effects of electrocautery, CO2 laser, and contact Nd:YAG laser on the healing of intestinal incisions. Fifteen piglets were used and the cutting and reanastomosing were performed by using all cutting methods in each animal in randomized order. Resection sites were 50 cm, 100 cm, and 150 cm distal to the ligament of Treitz. On the seventh day the bursting pressures were measured for each anastomosis. They were 172 +/- 17 mmHg for normal bowel segment and 133 +/- 12, 135 +/- 40, and 139 +/- 17 mmHg for electrocautery, CO2 laser, and Nd:YAG laser, respectively. There were no mortality, no anastomotic leaks, and no statistically significant differences in the bursting pressures, in histology, or in the healing of anastomotic sites, indicating that electrocautery, CO2 laser, and contact Nd:YAG laser scalpel can safely be used in the surgery of small intestine.

Recombination and deletion of sequences in shuttle vector plasmids in mammalian cells

Shuttle vector plasmids were constructed with directly repeated sequences flanking a marker gene. African green monkey kidney (AGMK) cells were infected with the constructions, and after a period of replication, the progeny plasmids were recovered and introduced into bacteria. Those colonies with plasmids that had lost the marker gene were identified, and the individual plasmids were purified and characterized by restriction enzyme digestion. Recombination between the repeated elements generated a plasmid with a precise deletion and a characteristic restriction pattern, which distinguished the recombined molecules from those with other defects in the marker gene. Recombination among the following different sequences was measured in this assay: (i) the simian virus 40 origin and enhancer region, (ii) the AGMK Alu sequence, and (iii) a sequence from plasmid pBR322. Similar frequencies of recombination among these sequences were found. Recombination occurred more frequently in Cos1 cells than in CV1 cells. In these experiments, the plasmid population with defective marker genes consisted of the recombined molecules and of the spontaneous deletion-insertion mutants described earlier. The frequency of the latter class was unaffected by the presence of the option for recombination represented by the direct repeats. Both recombination and deletion-insertion mutagenesis were stimulated by double-strand cleavage between the repeated sequences and adjacent to the marker, and the frequency of the deletion-insertion mutants in this experiment was again independent of the presence of the direct repeats. We concluded that although recombination and deletion-insertion mutagenesis were both stimulated by double-strand cleavage, the molecules which underwent the two types of change were drawn from separate pools.

Opiate modulation of glucose turnover in dogs

We examined the effect of opiate infusion and of opiate blockage on glucose turnover in the basal state, using isotope dilution techniques in trained conscious dogs (n = 5). After a primed-continuous infusion of 3-3H glucose to steady state specific activity (90 minutes), infusion of one of the following was given: D-met2 pro5 enkephalinamide (DMPE), a potent morphine-like opiate, 0.5 mus g/kg/min; naloxone, an opiate antagonist, 1.25 mg followed by 10 mus g/min; or saline control. Infusion of DMPE led to a fall in glucose from 92 +/- 3 to 87 +/- 3 mg/dL by 60 minutes (P less than 0.05), associated with a rise in glucose utilization (Rd) from 3.0 +/- 0.4 to 3.9 +/- 0.6 mg/kg/min by 30 minutes (P less than 0.05); a transient rise in glucose production (Ra; from 3.2 +/- 0.4 to 4.3 +/- 0.4 mg/kg/min; P less than 0.05). Changes in counterregulatory hormones did not account for these findings; insulin was unchanged during all infusions; glucagon showed small late rises at 75 minutes during both DMPE and naloxone infusion; cortisol rose by 30 and 15 minutes, respectively, of DMPE and naloxone infusion; epinephrine rose transiently after 5 minutes of naloxone but was unchanged during DMPE, and norepinephrine was unchanged throughout. Saline infusion had no effects on any of these indices. We conclude that a potent opiate with morphine-like effects (DMPE) can lower glucose in dogs by enhancing peripheral glucose utilization independently of hormonal changes.

Opiates modulate insulin action in vivo in dogs

To investigate the influence of opiates on insulin action in vivo, we induced mild physiological hyperinsulinaemia (15-20 mU/l) in five trained conscious dogs in the absence or presence of ongoing infusion with the opiate agonist D-met2-pro5-enkephalinamide (DMPE, 0.5 micrograms X kg-1 X min-1), or the opiate antagonist naloxone (1.25 mg followed by 1 microgram X kg-1 X min-1). The effects on glucose production and glucose utilization were measured by isotope dilution using 3-3H-glucose. Glucose fell similarly over 30 min in response to insulin in controls (0.021 +/- 0.003 mmol X l-1 X min-1), and both the DMPE and naloxone studies (0.016 +/- 0.002 mmol X l-1 X min-1 and 0.017 +/- 0.003 mmol X l-1 X min-1, respectively). In control dogs, insulin lowered glucose by transiently suppressing production by 0.028 +/- 0.006 mmol X kg-1 X min-1 at 20-30 min without changing utilization. In contrast, in both the DMPE and naloxone studies insulin lowered glucose by markedly raising utilization at 20 min by 0.094 +/- 0.017 and 0.139 +/- 0.022 mmol X kg-1 X min-1, respectively. Furthermore, insulin failed to suppress production in both DMPE and naloxone studies and, as plasma glucose fell, production rose in both treatment groups at 20 min by 0.045 +/- 0.012 and 0.089 +/- 0.022 mmol X kg-1 X min-1 respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug prevention of postoperative deep vein thrombosis. A compararative study of calcium heparinate and sodium pentosan polysulfate

Deep vein thrombosis and its sequel, pulmonary embolus, are possibly the greatest threats to recovery after surgical operation. In a randomized, controlled clinical trial in which the 125I-fibrinogen uptake test, Doppler ultrasound, and phlebography were used for diagnosis, it was found that low doses of calcium heparinate administered subcutaneously and sodium pentosan polysulfate intramuscularly were effective in preventing deep vein thrombosis (DVT), postoperatively. The incidence of DVT was as follows: 9% in the group treated with heparinate; 15% in the group treated with sodium pentosan polysulfate; nad 51% in the untreated control group.

Surface properties of membrane systems: apoprotein of the Folch-Lees proteolipid from beef-brain myelin

Structural proteins in biological membranes are bimodal and ideally possess a unique surface activity that should be amenable to study by monolayer techniques. Proteins so studied, however, display, of necessity, a surface activity that reflects the laboratory history of the protein. The Folch-Lees proteolipid apoprotein was isolated from calf-brain myelin in both an organic solvent (CHCl(3)-CH(3)OH-CH(3)COOH; 50:50:1) and water. The apoprotein did not spread as a film from water, but did spread readily from the organic solvent into films that had high saturation pressures. The partitioning of the apoprotein from organic solvent to water was found to be reversible, as was the gain and loss of surface activity. Infrared spectroscopy demonstrated that the preponderant structure in films of the apoprotein was not that of extended polypeptide chains. The results suggested that the preferred structures at the interface are bimodal coils of alpha helix. This structure can sustain the high film pressures observed, whereas beta keratin structures would build films with high surface viscosity and very low surface pressure.