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Biomedical subjects

J M Jenkins

Publications and source records attributed to J M Jenkins.

At least 37 records · Page 2Linked to original sources
PubMed1999

The influence of bacterial vaginosis on in-vitro fertilization and embryo implantation during assisted reproduction treatment.

There is growing evidence that the pathogenic effects of bacterial vaginosis may not be confined to the lower genital tract. Possible associations with infertility and effects on fertilization and implantation were studied in patients undergoing in-vitro fertilization (IVF) treatment. High vaginal swabs taken at the time of oocyte collection were assessed by Gram staining. The prevalence of bacterial vaginosis and of intermediate and normal flora in 301 patients was 25.6, 14.0 and 60.4% respectively. Bacterial vaginosis was more prevalent in patients with tubal (31.5%, n = 149) compared with non-tubal (19.7%, n = 152) infertility (odds ratio (OR) 1.87, CI 1.11-3.18, P = 0.02). Bacterial vaginosis did not have an adverse effect on fertilization rate. Further, no significant difference in implantation rates was seen when comparing bacterial vaginosis (15. 8%, OR 1.03, CI 0.66-1.61) and intermediate flora (13.1%, OR 0.82, CI 0.45-1.52) with normal flora (15.5%). Though confidence intervals around the observations were relatively wide, the findings suggest that routine screening for bacterial vaginosis in the hope of improving the success of IVF treatment is not justified. The prevention of complications in pregnancy associated with bacterial vaginosis might be a more relevant indication for screening at the time of IVF treatment, in particular patients with tubal disease, if treatment were shown to be effective for that particular purpose. However, antibiotic treatment before IVF has been shown to be positively disadvantageous for IVF by encouraging other organisms.

Adult↗
PubMed1999

Travel advice given by pharmacists.

BACKGROUND: In 1993 more than 1 million Swiss residents traveled to a tropical or subtropical country. Although most pretravel advice is given by general practitioners, a number of travelers also seek advice from pharmacists. Little is known about the quantity and quality of travel advice given or the sources of information used by this group. METHODS: One-hundred and twenty randomly selected pharmacists from three Swiss cantons were first interviewed in a cross-sectional study on the telephone. All study participants subsequently received a pretested questionnaire, in which most of the questions asked on the phone were repeated, with additional questions regarding the sources of information used for travel advice and the cooperation of general practitioners. Included in both parts of the study were two scenarios of fictive travelers seeking health advice for destinations frequently visited by Swiss tourists (Thailand and Kenya). RESULTS: Of 136 pharmacists approached, all who said they sometimes gave travel advice, agreed to participate (88%). Fifty-six percent of them give travel advice regularly (mean 2-3 times per month). General knowledge on the main health hazards was good, but for treatment of travelers' diarrhea, only 59% spontaneously mentioned the need for increased fluid intake, whereas 100 % recommended antidiarrheal drugs. Protection from the sun was mentioned only by 10 % of the respondents, and only 8 % said that the traveler should seek advice from a medical doctor. Over 95% could name the three most important measures against mosquito bites, although up to 20% still recommend Vitamin B1 as well. On the telephone, only 19% (for Thailand) and 31% (for Kenya) gave accurate advice on malaria protection, and 13% (for Thailand) and 3% (for Kenya) could make correct recommendations about vaccination. However, more than 50% said that in practice they would consult documentation before giving any advice, with the Bulletin of the Federal Office of Health (BFOH) being the most commonly used source of information. In the questionnaire interview, where documentation was used, the accuracy of advice increased, especially for malaria protection (74% correct for Thailand and 93% for Kenya). CONCLUSIONS: The overall knowledge of Swiss pharmacists on travel medicine issues is satisfactory. Specific questions need further attention, such as treatment of travelers' diarrhea, sun protection and advice on malaria prophylaxis and vaccinations. For the latter two, clients should also consult a medical doctor. Collaboration between doctors and pharmacists, and the consistency of the advice given, are important in improving compliance. Reliable information sources are available in pharmacies and are used.

Cross-Sectional Studies↗
PubMed1998

The relation between immunoglobulin G antibodies to Chlamydia trachomatis and poor ovarian response to gonadotropin stimulation before in vitro fertilization.

OBJECTIVE: To determine whether a relation exists between previous exposure to Chlamydia trachomatis and impaired ovarian response to gonadotropin stimulation. DESIGN: Controlled clinical study. SETTING: Two university IVF centers. PATIENT(S): Two hundred forty-two patients receiving IVF treatment and 81 control patients. Ninety-four patients with a poor response to IVF, defined by cycle cancellation in response to a daily stimulation dose of 300 IU of FSH, and 148 patients with a good response were matched for age. Twenty-eight pregnant controls and 53 controls of proven fertility also were included. INTERVENTION(S): Serum samples were obtained from patients and controls. Serum levels of immunoglobulin (Ig) G antibodies to C. trachomatis were determined by ELISA. MAIN OUTCOME MEASURE(S): The prevalence of serum IgG antibodies to C. trachomatis in critically defined poor responders was compared with that of age-matched good responders. RESULT(S): A significantly higher proportion of poor responders had serum IgG antibodies to C. trachomatis compared with good responders (44.7% and 30.4%, respectively). Patients undergoing IVF had a significantly higher prevalence of IgG antibodies to C. trachomatis (36%) than did either pregnant or nonpregnant controls (12%). CONCLUSION(S): A significantly higher prevalence of serum IgG antibodies to C. trachomatis was observed in critically defined poor responders, suggesting a possible detrimental effect of C. trachomatis on subsequent ovarian function.

Adult↗
PubMed1998

A testing system for implantable cardioverter defibrillators.

Implantable cardioverter defibrillator (ICD) testing during the implantation process is important in order to avoid repeated induction of arrhythmias, which extends the implantation procedure and poses a risk to the patient. Hence, an in vitro testing system has been designed to assist optimal device programming and avoid repetitive inductions. The system includes a high-speed computer with A/D and D/A subsystems. Software has been designed to eliminate repeated arrhythmia induction by real-time capture and storage of the electrogram. Subsequently, the electrogram can be replayed into ICD software simulators at a variety of settings to determine candidate programming parameters. To validate the simulation system, signals were fed directly to an ICD via an attenuator. Output event markers were captured simultaneously with the signal into a digital file to assess the device performance. Four ventricular tachycardia (VT), three supraventricular tachycardia, (SVT), three atrial flutter (AFL), three atrial fibrillation (AF), and ten ventricular fibrillation (VF) passages were used to verify the system. Test settings were 110-160 beats/min for detection rate and 5 seconds for shock delay. The simulator and ICD detected the episodes for all passages at the 110 beats/min setting. For the setting of 160 beats/min, two VTs, two SVTs, three AFLs, and nine VFs were detected by the device, but no Afb triggered a shock. The simulator detection criteria were met by two VTs, two SVTs, three AFLs, ten VFs, and one AF. The mean detection time was 6,869-7,330 ms (110-160 beats/min) for the simulator and 7,840-8,170 ms for device. Comparison of results showed general agreement between simulator and device. Results demonstrated that device behavior at a variety of settings can be elucidated by the simulator for selection of optimal performance. The automated system can also function as a test bed for evaluation of new algorithms during device development and design.

Algorithms↗
PubMed1998

Comprehensive scheme for detection of ventricular fibrillation for implantable cardioverter defibrillators.

Implantable cardioverter defibrillators (ICDs) detect and defibrillate ventricular fibrillation (VF) and ventricular tachycardia (VT). Other therapies which use less energy are also available to terminate VT. Previous studies have shown that ICD rate schemes often misdiagnose VT as VF. In this study, an improved VF classification scheme was designed and tested, which employs the classic rate criteria plus paired signal concordance (PSC); PSC uniquely detects VF where VT and VF rates overlap (220-340 ms). Two signals from a bipolar pair (1 cm) recorded in a unipolar sense exhibit similar signal shape for concordant rhythms, such as sinus rhythm and VT, and disconcordance for VF. Once the rate criterion is met, PSC is measured by the peak normalized cross-correlation coefficient calculated over the depolarization. Variability, measured by a modified range, determined the contextual diagnosis over a passage. Sinus rhythm (20), VT (12), VF (22), atrial fibrillation (10), sinus rhythm with ventricular premature depolarizations (7), and polymorphic VT (4) passages were recorded from 38 patients. Rate-PSC was tested with unfiltered, digitized signals (1-500 Hz, 1,000 samples per second) and with filtered, downsampled signals (1-50 Hz, 100 samples per second). Sensitivity values, or percentage of correct VF detection, and specificity values, or detection of all other rhythms, were generated and compared with simulations of three commercial ICDs programmed to similar settings as rate-PSC and to nominal settings. The sensitivity values for rate-PSC with unfiltered and with filtered signals and for ICDs with 220 ms and with nominal settings were 100%, 100%, 48-80%, and 100%, respectively; the corresponding specificity values were 95%, 83%, 93%, and 7-13%, respectively. It was concluded that the rate-PSC scheme was able to reliably separate VF from other rhythms, even rhythms that have a variable morphology or variable rate. With the confidence of accurate VF detection, use of low-energy therapies for non-VF rhythms will increase device longevity and enhance patient comfort.

Computer Simulation↗
PubMed1998

Ventriculoatrial conduction metrics for classification of ventricular tachycardia with 1:1 retrograde conduction in dual-chamber sensing implantable cardioverter defibrillators.

The introduction of dual-chamber sensing in implantable cardioverter defibrillators (ICDs) has greatly reduced the incidence of false detection due to supraventricular tachycardias. The remaining arrhythmias which serve to confound classification are supraventricular tachycardias (SVTs) with 1:1 anterograde conduction and ventricular tachycardias (VT) with 1:1 retrograde conduction. An algorithm has been designed and tested (28 patients) which employs ventriculoatrial (VA) conduction measurements to separate 1:1 VTs from 1:1 SVTs. A study was conducted to assess realistic VA interval boundaries for classification of arrhythmias with 1:1 retrograde atrial conduction. Intracardiac atrial and ventricular recordings of 7 passages of VT with retrograde conduction, 12 passages of atrioventricular nodal reentrant tachycardia (AVNRT), 3 passages of atrial tachycardia (AT), 8 passages of sinus tachycardia (ST), and 2 passages of orthodromic reentrant tachycardia (ORT) were analyzed. Automated real-time atrial and ventricular waveform recognition was performed on each passage and VA intervals were measured. Separation of VT with retrograde conduction from other 1:1 supraventricular tachycardias was effected by imposing discrete VA interval boundaries. VA boundaries of 80 ms to 234 ms classified 1:1 VT with 100% sensitivity (SENS) and 80% specificity (SPEC). In addition, the lower boundary completely classified AVNRT with 100% SENS and 100% SPEC, and all passages of ST were contained above the upper boundary. These findings could be of importance in algorithms for next-generation implantable cardioverter defibrillators which include two-chamber (atrial and ventricular) sensing and two-chamber interval measurements.

Algorithms↗
PubMed1998

Collagen IX: evidence for a structural association between NC4 domains in cartilage and a novel cleavage site in the alpha 1(IX) chain.

Collagen IX, a structural component of the extracellular matrix of connective tissues, is synthesized as long and short forms which contain or lack, respectively, a 27 kDa non-collagenous (NC) 4 domain at the N-terminus of the alpha 1(IX) chain of the molecule. The long form occurs in cartilage and developing cornea, but not in vitreous, suggesting a specialized function for the NC4 domain, perhaps by interacting with other macromolecules. To test this hypothesis, embryonic chick cartilage was treated with DTSSP, dissociated with bacterial collagenase, and the NC4-containing DTSSP-cross-linked protein complexes examined and purified. Analysis of cartilage extracts using an anti-NC4 antibody, and of purified NC4-containing complexes, identified a predominant NC4 dimer. A naturally-occurring N-terminal fragment of the alpha 1(IX) chain, whose size is equivalent to the NC4-COL3-NC3 domains of the chain, was identified. Association of collagen IX molecules via NC4 domains and the existence of a cleavage site close to the NC3 domain of the molecule are likely to be of primary importance in the growth and remodeling processes of cartilage, in health and disease.

Animals↗
PubMed1998

The incidence of lower-pole nephrolithiasis--increasing or not?

OBJECTIVE: To determine if the incidence of lower-pole nephrolithiasis is increasing. METHODS: A previously published meta-analysis of trends in the location of stones in the kidney, using data from 1984 to 1992, determined the percentage of lower pole stones in 26,722 kidney stones treated by extracorporeal shockwave lithotripsy (ESWL). We performed prospective studies on all patients treated by ESWL for a single renal stone (not manipulated from the ureter) in two organizations: at Lithotripters Inc., 47,303 stones were treated with ESWL by 1000 urologists in private practice from 1989 to 1995. At the Midwest Urologic Stone Unit, 9357 stones were treated with ESWL by 200 urologists in private practice from 1987 to 1995. The distribution of stones in both samples was compared with that reported earlier. RESULTS: The meta-analysis for stone location trends from the previously published article suggested that the percentage of kidney stones in the lower pole at ESWL increased erratically from 1984 to 1989 but was then stable for 3 years. The Lithotripters Inc. sample showed an essentially constant incidence from 28% in 1990 to 30% in 1995, and the Midwest Urologic Stone Unit sample showed an essentially constant incidence from 35% in 1988 to 36% in 1995. CONCLUSION: The incidence of lower pole nephrolithiasis has remained stable from 1990.

Humans↗
PubMed1998

Elective bedside surgery in critically injured patients is safe and cost-effective.

OBJECTIVE: The success of elective minimally invasive surgery suggested that this concept could be adapted to the intensive care unit. We hypothesized that minimally invasive surgery could be done safely and cost-effectively at the bedside in critically injured patients. SUMMARY BACKGROUND DATA: This case series, conducted between October 1991 and June 1997 at a Level I trauma center, examined bedside dilatational tracheostomy (BDT), percutaneous endoscopic gastrostomy (PEG), and inferior vena cava (IVC) filter placement. All procedures had been performed in the operating room (OR) before initiation of this study. METHODS: All BDTs and PEGs were performed with intravenous general anesthesia (fentanyl, diazepam, and pancuronium) administered by the surgical team. IVC filters were placed using local anesthesia and conscious sedation. BDTs were done using a Ciaglia set, PEGs were done using a 20 Fr Flexiflow Inverta-PEG kit, and IVC filters were placed percutaneously under ultrasound guidance. Cost difference (delta cost) was defined as the difference in hospital cost and physician charges incurred in the OR as compared to the bedside. RESULTS: Of 16,417 trauma admissions, 379 patients (2%) underwent 472 minimally invasive procedures (272 BDTs, 129 PEGs, 71 IVC filters). There were four major complications (0.8%). Two patients had loss of airway requiring reintubation. Two patients had an intraperitoneal leak from the gastrostomy requiring operative repair. No patient had a major complication after IVC filter placement. Total delta cost was $611,994. When examined independently, the cost was $324,224 for BDT, $164,088 for PEG, and $123,682 for IVC filter. OR use was reduced by 506 hours. CONCLUSIONS: These bedside procedures have minimal complications, eliminate the risk associated with patient transport, reduce cost, improve OR utilization, and should be considered for routine use in the general surgery population.

Adult↗
PubMed1997

Increased follicular fluid total and free cortisol levels during the luteinizing hormone surge.

OBJECTIVE: To determine the changes in follicular fluid (FF) total and free cortisol during the LH surge in naturally ovulating women. PATIENT(S): Twenty-six women having diagnostic laparoscopy during the follicular phase of normal menstrual cycles were selected. INTERVENTION(S): Blood samples were collected 1 day before, the day of, and 1 day after surgery and the results of serum E2 and LH were used to divide the cycles retrospectively into pre- and post-LH surge groups. Follicular fluid was collected during laparoscopy. MAIN OUTCOME MEASURE(S): Serum P, total and free cortisol, and FF volume, E2, P, total cortisol, and free cortisol were measured on the day of surgery. RESULT(S): Median serum and FF P levels were significantly higher in the post-LH surge group compared with the pre-LH surge group (0.54 versus 1.54 ng/mL [1.7 versus 4.85 nmol/L] and 5.03 versus 28.0 micrograms/mL [15.8 versus 88.0 mumol/L], respectively). Follicular fluid volume also increased significantly after the surge (2.5 versus 4.5 mL). Median serum total and free and percent free cortisol were higher after the surge, although not significantly. In contrast, FF total, free, and percent free levels increased dramatically between pre- and post-LH surge samples (4.41 versus 43.6 ng/mL [16.0 versus 158 nmol/L], 0.138 versus 6.68 ng/mL [0.5 versus 24.2 nmol/L], and 3.3% versus 15.0%, respectively; P < 0.05). CONCLUSION(S): An increase in total and free cortisol occurs in the follicle during the LH surge. Cortisol and its regulation by 11 beta-hydroxysteroid dehydrogenase therefore may exert a physiologic role in oocyte maturation or ovulation.

Estradiol↗
PubMed1997

The possible role of the immune system in the aetiopathogenesis of ovarian hyperstimulation syndrome.

This review examines recent evidence suggesting a role for the immune system, in particular cytokines, in the pathogenesis of ovarian hyperstimulation syndrome (OHSS). Ovarian tissue is known to contain cells capable of producing a range of immunological mediators and the concentrations of these have been shown to be elevated in serum and ascitic fluid from women with established OHSS. Available evidence points to a role for vascular endothelial growth factor and interleukin-2, possibly acting through other intermediary cytokines, in the pathogenesis of OHSS. However, each individual has a unique cytokine profile and several cytokines may share biological actions, making it difficult to interpret data on isolated cytokine concentrations from relatively small numbers of patients. Improved understanding of the role of the immune system in the development of OHSS may have implications for the prediction, prevention and management of this iatrogenic condition.

Cytokines↗
PubMed1997

The detection and confirmation of 11 beta-hydroxysteroid dehydrogenase type 1 transcripts in human luteinized granulosa cells using RT-PCR and plasmid pUC18.

The activity of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) in human granulosa cells has been shown to be associated with the outcome of treatment following in-vitro fertilization and embryo transfer. There are two known isoforms of 11 beta-HSD which differ significantly in their actions and co-factor requirements. The net activity of 11 beta-HSD which differ significantly in their actions and co-factor requirements. The net activity of 11 beta-HSD within the human ovary is unclear, but may be of particular importance within the ovarian follicle in regulating possible glucocorticoid influences on the oocyte. This study presents preliminary information regarding establishment of techniques to identify transcripts of the 11 beta-HSD isoforms within human granulosa cells and human cumulus cells using reverse transcription-polymerase chain reaction. In view of the high expression of the type 1 11 beta-HSD isoform and the possibility of other 11 beta-HSD isoforms in the ovary, plasmid technology was used to confirm the technique specifically identifying the known isoforms.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1997

Cost-effective method for bedside insertion of vena caval filters in trauma patients.

BACKGROUND: The need for patient transport for inferior vena cava (IVC) filter placement impacts patient safety, comfort, charges, and nursing care. Bedside, ultrasound-guided IVC filter placement may offer an acceptable, cost-effective alternative. METHODS: Prospective cohort study of 55 consecutive trauma patients requiring IVC filter placement. During a 13-month period (August of 1995-September of 1996), patients meeting criteria for IVC filter were evaluated. Complications were recorded, and the potential financial savings were determined. RESULTS: Of 3,172 trauma admissions, 55 patients met IVC filter criteria and 49 patients had IVC filters placed under ultrasound guidance. In six patients (10.9%), ultrasound guided filter placement failed. There were four complications in four patients (8.2%). Over 13 months, charges were reduced by $69,800 when compared with radiology suite placement and $118,300 when compared with operative placement. CONCLUSIONS: Ultrasound guided, bedside placement of IVC filters is a safe, cost-effective method of pulmonary embolism prophylaxis in select trauma patients.

Adolescent↗
PubMed1997

Band-limited morphometric analysis of the intracardiac signal: implications for antitachycardia devices.

Inappropriate electrical therapy and power efficiency play a major role in algorithm implementation for antitachycardia devices (ATD) that capture, store, and analyze the patient electrogram as an adjunct to rate determination. Morphologically based algorithms have been demonstrated to improve specificity, thereby decreasing occurrences of inappropriate electrical therapy. However, morphologically based algorithms are power demanding. Optimization of power efficiency can be achieved by eliminating unnecessary algorithmic computation, but must not compromise the effectiveness of algorithms, which perform direct analysis on raw signals. Significant reductions can be achieved by reduced sampling rates, which allow for increased overall ATD efficiency via concomitant decreases in computation and data storage. This investigation determined the upper and lower bounds for filter cut-off frequency beyond which detection precision by an established morphometric method for arrhythmia classification, correlation waveform analysis (CWA), was unfavorable. Four measurement statistics were used. In ten patients with inducible VT and VF, all bipolar intraventricular electrograms were classified correctly with a minimum passband of 10-50 Hz using any of the four measurement statistics. There was > or = 80% correct classification using all four measurement statistics with passbands having low frequency cutoffs < or = 15 Hz and high frequency cutoffs > or = 50 Hz. Correct classification of > or = 90% of unipolar electrograms during NSR, VT, and VF occurred using all four measurement statistics with a passband of 1-50 Hz. There was > or = 80% correct classification with passbands 1, 10, 15, or 20-500 Hz and 10-50 Hz. The classification of NSR, VT, and VF was most accurate on an intrapatient basis. Accuracy decreased using an interpatient rhythm classification. Optimum filter settings of 1-50 Hz and 10-50 Hz were determined for unipolar and bipolar electrograms, respectively. Sampling data at 120 Hz was found to be sufficient. Bipolar electrode configuration statistically outperformed unipolar data. In conclusion, morphometric analysis of bipolar and unipolar intraventricular electrograms appears to be achievable using band limited data and reduced sampling rates.

Algorithms↗
PubMed1997

Analysis of the intraventricular electrogram for differentiation of distinct monomorphic ventricular arrhythmias.

This study investigated the effectiveness of correlation waveform analysis for identifying different ventricular electrogram morphologies of multiple VTs in the same patient. Patients with implantable antitachycardia devices are commonly subject to the occurrence of more than one distinct monomorphic VT. Each of these VTs may have unique therapeutic alternatives for termination. VTs with identical and different monomorphic configurations were recorded (1-500 Hz) using distal bipolar (1 cm) and distal unipolar electrograms from the right ventricular apex. Thirty-six distinct monomorphic VTs induced in 15 patients were analyzed. Nine VTs with identical morphologies (12/12 surface ECGs) were induced twice and used as a control. A template was created for each VT induced. Correlation waveform analysis was used to compare each depolarization of all other VTs induced subsequently in the same patient. The mean correlation coefficient (p mu) of cycle-by-cycle analysis was used as a discriminant function: p mu > or = 0.95 was considered matched; and p mu < 0.95 was considered distinct. From the control population, VTs were successfully classified as identical in 9 of 9 cases (100%) using both bipolar and unipolar electrograms. VTs with different monomorphic configurations were successfully classified as being different in 31 of 33 cases (94%) using bipolar electrogram analysis and in 29 of 33 cases (88%) using the unipolar. Template matching is effective for detecting: (1) the recurrence of VTs, which are identical; and (2) the occurrence of a VT with a different configuration. This method appears effective using either unipolar or bipolar intracardiac waveforms.

Aged↗