Validated assays for the determination of gemcitabine in human plasma and urine using high-performance liquid chromatography with ultraviolet detection

Procedures are described for the determination of gemcitabine, a new anti-tumor agent, and its uridine metabolite in human plasma and in human urine. The sample preparation for the plasma assay involves precipitation of plasma proteins with isopropanol and ethyl acetate. Following this, the solids are discarded and the supernatant is evaporated to dryness. For the urine assay, the sample is diluted with methanol and evaporated to dryness. For both procedures, the residue is reconstituted in mobile phase prior to injection into a normal-phase (amino column) liquid chromatographic system followed by UV detection at 272 nm. The limits of quantitation for both compounds are 50 ng/ml in plasma and 20 micrograms/ml in urine. The procedures were used to provide pharmacokinetic data for both compounds in man following the intravenous administration of a 1000 mg/m2 dose of gemcitabine.

It may be time to redefine security as a "profit center" in the healthcare industry

Security, say the authors, should be viewed as a profit center that protects the patients, staff, visitors, property, and assets of healthcare organizations from violent crime, injury, theft, or vandalism ... and the resulting devastating litigation. Security services, which protect the "bottom line," should be a central part of any healthcare organization.

Chest physiotherapy in cystic fibrosis: a comparative study of autogenic drainage and the active cycle of breathing techniques with postural drainage

BACKGROUND--Autogenic drainage has been suggested as an alternative method of chest physiotherapy in patients with cystic fibrosis. In this study autogenic drainage was compared with the active cycle of breathing techniques (ACBT) together with postural drainage. METHODS--Eighteen patients with cystic fibrosis took part in a randomised two-day crossover trial. There were two sessions of one method of physiotherapy on each day, either autogenic drainage or ACBT. The study days were one week apart. On each day the patients were monitored for six hours. Mucus movement was quantified by a radioaerosol technique. Airway clearance was studied qualitatively using xenon-133 scintigraphic studies at the start and end of each day. Expectorated sputum was collected during and for one hour after each session of physiotherapy. Pulmonary functions tests were performed before and after each session. Oxygen saturation (SaO2) and heart rate were measured before, during, and after each session. RESULTS--Autogenic drainage cleared mucus from the lungs faster than ACBT over the whole day. Both methods improved ventilation, as assessed by the xenon-133 ventilation studies. No overall differences were found in the pulmonary function test results, but more patients had an improved forced expiratory flow from 25% to 75% with autogenic drainage, while more showed an improved forced vital capacity with ACBT. No differences were found in sputum weight and heart rate, nor in mean SaO2 over the series, but four patients desaturated during ACBT. CONCLUSIONS--Autogenic drainage was found to be as good as ACBT at clearing mucus in patients with cystic fibrosis and is therefore an effective method of home physiotherapy. Patients with cystic fibrosis should be assessed as to which method suits them best.

An experimental test of retention in residential and outpatient programs

Previous studies of residential and outpatient drug treatment programs have found that retention is higher in residential than in outpatient programs. This study attempts to verify previous findings by conducting an experiment that controls for ecological, self-selection, and program content biases. The Houston Recovery Campus is a research-focused, multiple-provider drug treatment facility for the indigent of Harris County, Texas. During the study period, 646 applicants were randomly assigned to two comparable 28-day programs. The first program was a residential program; the second was an outpatient day treatment program. Twenty-eight day retention rates were significantly higher for the residential program (76%) compared to the day treatment program (64%).

Community screening for diabetes. Low detection rate in a low-risk population

OBJECTIVE

To evaluate glucose-based community screening for diabetes with regard to detection rate.

RESEARCH DESIGN AND METHODS

A retrospective analysis of a community-screening questionnaire data base that included a screening for blood glucose. Referred subjects had fasting glucose levels > 6.4 mM (115 mg/dl) or postprandial levels > or = 8.9 mM (160 mg/dl). An attempt was made to contact referred subjects and to ascertain whether follow-up was undertaken and current status. A random sample of subjects not meeting the glucose criteria (nonreferred) also was contacted in an analogous fashion to referred subjects.

RESULTS

In 2,016 questionnaires, glucose-based referral criteria were exhibited by 148 (7.3%) individuals, and subsequent evaluation data were available for 111. Of those 111 individuals, 37 (33%) knew they had diabetes before the screening, and 39 (36%) did not seek further evaluation. Of the remaining 35 subjects, 6 (13%) were told of their new diagnosis of diabetes, and 29 were told they did not have diabetes. Three of 50 nonreferred subjects knew of their diabetes before screening. Thirty percent (14 out of 47) of nonreferred subjects underwent subsequent evaluation, although they were not told to do so. A single new case of diabetes occurred in the nonreferred group.

CONCLUSIONS

Community screening for diabetes that is based on measured glucose is of low yield. The known problems of glucose-based screening, coupled with its low yield, make a glucose-based approach difficult to justify. These results indicate that glucose-based community screening should be done only under the careful supervision of a health professional who is trained both in glucose measurement instrumentation and in screening.

Large bowel cancer following gastric surgery for benign disease: a cohort study

Early studies suggested that gastric surgery for benign ulcer disease was associated with a subsequent increase in the risk of large bowel cancer. Dietary fats, altered bacterial flora, and secondary bile acids are considered to play a major role in the disease etiology. Gastric surgery is known to alter bile salt metabolism as well as bacterial flora in the colon. This cohort study was designed to investigate the risk of large bowel cancer following gastric surgery for benign ulcer disease and to identify potential patient and treatment characteristics that may be associated with this risk. A cohort of 15,983 males was selected from Department of Veterans Affairs hospital admissions in 1970 and 1971. The exposed group (n = 7,609) included all males treated with gastric surgery (resection or vagotomy and drainage) for benign ulcer disease. The unexposed group (n = 8,374) was a random sample of all other male patients from the same time period and database. All subjects were followed through 1989 to identify vital status and cause of death. Deaths were identifiable by computerized linkage of the subjects' social security numbers with the Department of Veterans Affairs Beneficiary Identification Record Locator System and the National Death Index. The cause of death was documented by two certified nosologists from the death certificates of 99% of the deceased patients. Statistical analyses included estimations of risk based on standardized mortality ratios and standardized risk ratios. In this selected cohort, no increase in large bowel cancer risk was detected (risk ratio = 0.81, 95% confidence interval 0.62-1.05). The type of surgical procedure, ulcer diagnosis, age at the time of surgery, and length of follow-up did not alter the risk estimates. Unlike the previously identified increase in gastric cancer risk following ulcer surgery, no elevation in the risk of large bowel cancer following such surgery was detected in this study. Factors that may alter gastric surgery sequelae and resultant site-specific cancer risks deserve further investigations.

Medical education and health system reform

There is increasing pressure on medical schools to produce more primary care physicians and fewer specialists. Health system reform proposals which rely on a "gatekeeper" approach will keep public attention on this issue. Educators at the University of Iowa say physician training must meet all of society's needs.

Characterization of a Plasmodium falciparium mutant that has deleted the majority of the gametocyte-specific Pf11-1 locus

We identified a gametocyte-specific protein of Plasmodium falciparum called Pf11-1 and provide experimental evidence that this molecule is involved in the emergence of gametes of the infected erythrocyte (gametogenesis). A mutant parasite clone, which has deleted over 90% of the Pf11-1 gene locus, was an important control to establish the gametocyte-specific expression of the Pf11-1. Molecular analysis of the Pf11-1 deletion indicates that it is presumably due to a chromosome breakage with subsequent 'healing' by the addition of telomeric heptanucleotides. Moreover, similar DNA rearrangements are observed in most of the laboratory isolates during asexual propagation in vitro.

Conductances evoked by light in the ON-beta ganglion cell of cat retina

When a bar of light (215 x 5000 microns) illuminates the receptive field of an ON-beta ganglion cell of cat retina, the cell depolarizes. Intracellular recording from the cat eyecup preparation shows that this depolarization is due to an increase in conductance (2.4 +/- 0.6 nS). Different phases of this depolarization have different reversal potentials, but all of these reversal potentials are more positive than the cell's resting potential in the dark. When the light is turned on, there is an initial transient depolarization; the reversal potential measured for this transient is positive (23 +/- 11 mV). As the light is left on, the cell partially repolarizes to a sustained depolarization; the reversal potential measured for this sustained depolarization is close to zero (-1 +/- 5 mV). When the light is turned off, the cell repolarizes further; the reversal potential measured for this repolarization is negative (-18 +/- 7 mV), but still above the resting potential in the dark (-50 mV). To explain this variety of reversal potentials, at least two different synaptic conductances are required: one to ions which have a positive reversal potential and another to ions which have a negative reversal potential. Comparing the responses to broad and narrow bars suggests that these two conductances are associated with the center and surround, respectively. Finally, since an ON-beta cell in the area centralis receives about 200 synapses, these results indicate that a single synapse produces an average conductance increase of about 15 pS during a near-maximal depolarization.

Methodological issues in the administration of multiple doses of smoked cocaine-base in humans

Many methodological issues exist in human laboratory research with smoked cocaine-base that include safety, precision of dose delivery of smoked cocaine, and the lack of an adequate placebo. All of these issues are particularly apparent with studies involving multiple doses of cocaine. Addressing these concerns is important in conducting parametric studies that require examining dose-response effects. The purposes of this study were to determine: 1) the safest interval between doses to deliver smoked cocaine; 2) the accuracy or reproducibility of administering precise and multiple doses of cocaine; 3) the potential for using a control dose of cocaine; and 4) the influence of multiple doses on these parameters. Six black males were given 10 doses of either 5 or 35 mg of cocaine-base at 15-, 30-, and 45-min intervals. The dependent measures included physiological, subjective, and performance responses. These measures were taken prior to dosing and at specific time intervals after each dose of smoked cocaine. The results showed: 1) dosing at 30-min intervals allowed sufficient time for recovery of blood pressure and heart rate to permit up to 10 doses to be safely administered; 2) reproducible blood cocaine levels were obtained with repeated dosing using a heated wire-coil device; 3) significant differences were observed between the 5- and 35-mg dose with 5 mg being a low enough dose to produce minimal effects; 4) acute tolerance was evidenced with multiple doses of cocaine for most of the measures; and 5) considerable between- and within-subject variability was observed in the pattern of responses to cocaine.

Insulin sensitivity and metabolic clearance rate of insulin in cystic fibrosis

We have evaluated the metabolic clearance rate (MCR) of insulin and insulin sensitivity in 12 older patients with cystic fibrosis (CF) using the hyperinsulinemic euglycemic clamp method. Compared with a control group matched accurately for age and body mass index (BMI), the MCR of insulin was significantly enhanced in CF CF = 21.85 +/- 1.17 v controls = 16.01 +/- 0.92 mL/kg/min, P < .005), and this difference persisted after correction for lean body mass ([LBM] CF = 26.32 +/- 1.28 v controls = 19.09 +/- 1.09 mL/kg LBM/min, P < .005). Glucose disposal rates (M) were similar in the two groups during the clamp (CF = 7.28 +/- 0.41 v controls = 6.83 +/- 0.60 mg/kg/min, P > .5), but the insulin sensitivity index, M/I x 100 (I = steady-state insulin concentration), was markedly increased in the CF group (CF = 17.62 +/- 1.30 v controls = 11.75 +/- 0.71, P < .005). In conclusion, the MCR of insulin is enhanced in CF, which is in keeping with previous observations on drug metabolism in this disorder. Second, insulin sensitivity is increased in CF, and this points to a compensatory mechanism to counteract the insulinopenia.

Matrix-assisted laser desorption mass spectrometric analysis of a pegylated recombinant protein

Matrix-assisted laser desorption ionization mass spectrometry (MALDI) has been investigated as a technique for the characterization of recombinant stem cell factor that had been covalently modified with polyethylene glycol (PEG) chains. The attachment of PEG chains produces a heterogeneous mixture of protein species that differ by 6000 Da. These differences in molecular weight could be readily determined by MALDI. The potential of MALDI as a general strategy for characterizing PEG-modified proteins is discussed.

Treatment of fecal impaction with pulsed irrigation enhanced evacuation

PURPOSE

A new method of treating fecal impaction is described, selecting patients that would otherwise have required operative disimpaction.

METHOD

Using the pulsed irrigation enhanced evacuation device, individuals were selected for treatment based on evidence of massive fecal impaction on physical examination or abdominal x-ray.

RESULTS

Fourteen individuals were treated for fecal impaction. The patients ranged in age from 13 to 86 years. Only one patient required intravenous sedation, an elderly patient with Alzheimer's disease. The treatment was successful in each case, although repeated treatment was often necessary. No morbidity arose from the treatment. By the midpoint in our study, because of the success of this treatment, no patient required hospitalization for impaction.

CONCLUSION

Pulsed irrigation enhanced evacuation has been in our experience a simple, quick, and effective treatment for severe fecal impaction.

Dose-response and concentration-response relationships: clinical and regulatory perspectives

There are a number of effective but highly toxic drugs that exhibit a narrow therapeutic index and marked intersubject variability in pharmacokinetics (PK). Examples of these drugs included digoxin, theophylline, aminoglycosides, and anticancer (methotrexate) and immunosuppressive agents (cyclosporin A and FK-506). Optimal therapy with such drugs requires therapeutic drug monitoring (TDM) in order to safely obtain the desired clinical effects. The success of concentration-guided therapy with these drugs underscores the importance of using TDM and pharmacodynamic response (PD) to establish an appropriate balance of efficacy and toxicity through individualization of dosing. Although dose control has been the traditional paradigm for defining efficacy, safety, and dose response, it has recently been proposed that a concentration-oriented strategy of drug evaluation may facilitate the discovery of optimal doses and expedite new drug approval. However, as in medical therapeutics, the implementation of concentration-guided drug development may add to the complexity and cost. Therefore, it is important to assess the relative merits and limitations of dose-response and concentration-response (CR) strategies for establishing rational dosage information (e.g., a useful therapeutic range). Critical factors that have an effect on the ability to characterize dose-response/concentration-response relationships in clinical trials include study design, compliance, method of analysis, and sources of pharmacologic (PK-PD) variability. In this report, we describe the state of the art, based on a selected survey of successful dose-response studies. We give an example of a promising alternative strategy for evaluating CR for an immunosuppressive drug (FK-506) based on target drug concentrations extrapolated from preclinical models.

Musculoskeletal dysfunction of the neck in migraine and tension headache

In this prospective controlled study, thirty-seven migraine and/or tension headache patients and thirty-seven age and sex matched controls were examined for evidence of musculoskeletal dysfunction in the neck. The examination consisted of clinical range of motion testing of neck rotation, sidebending, flexion and extension while in the sitting position. The headache group had more abnormal physical findings than the control group. Although the difference for each particular motion test, taken by itself, was not statistically significant, two or more abnormalities in combination was found to reach a .05 confidence level of significance. It is proposed therefore that musculoskeletal dysfunction of the neck is a contributing factor to the etiology of migraine and tension headache.

Latex anaphylaxis

BACKGROUND

Unexplained vascular collapse, airway obstruction, shock, and death after procedures as innocuous as barium enema or anorectal manometry have recently been shown to be due to allergy to latex and anaphylactoid reaction.

METHOD

To review existing medical literature on latex anaphylaxis and to determine who is most at risk and what methods might best prevent morbidity from this condition.

RESULTS

Those most at risk for this catastrophe are patients whose mucous membranes have been extensively exposed to latex, such as patients with spina bifida who frequently undergo urethral catheterization and individuals who have had many previous operative procedures:

CONCLUSIONS

Avoidance of latex exposure is the best prophylaxis in high-risk groups. Prompt resuscitation is critical once the syndrome becomes clinically apparent.

Clinical correlates of acoustic neuroma volume

A computer-assisted, MRI-based technique of tumor volume determination was used to correlate preoperative hearing levels and long-term postoperative facial function with acoustic neuroma volume. Preoperative hearing was studied in a group of 41 patients subjected to direct tumor volume calculations and in another group of 131 patients in whom volume was extrapolated from the acoustic neuroma volume-diameter relation. Similarly postoperative facial function was correlated with acoustic neuroma volume in another 864 patients in whom long-term follow-up was available. Preoperative hearing levels were found not to be significantly related to tumor volume. However, postoperative facial function was significantly associated with tumor volume and was best predicted as a nonlinear function of diameter. Thus, tumor volume changes are important considerations in the clinical management of acoustic neuromas. Patients should be advised that even small changes in tumor diameter (especially in larger tumors) can result in tumor volume changes that may be associated with significant changes in postoperative facial function.