Accurate calibration of S(2) and interferometry based multimode fiber characterization techniques.

We present a novel method to validate the relative amount of power carried by high order modes in a multimode fiber using a Spatial and Spectral (S(2)) imaging technique. The method can be utilized to calibrate the S(2) set-up and uses Fresnel reflections from a thin glass plate to compare theoretical values with experimental results. We have found that, in the most general case, spectral leakage and sampling errors can lead S(2) to underestimate the multipath interference (MPI) of high order modes by several decibels, thus significantly impairing the result of the measurement. On the other hand, by applying suitable corrections as described in this work, we demonstrate that the S(2) produces MPI estimates that are accurate to within 1dB or better.

Optical side scattering radiometry for high resolution, wide dynamic range longitudinal assessment of optical fibers.

Current optical reflectometric techniques used to characterize optical fibers have to trade-off longitudinal range with spatial resolution and therefore struggle to provide simultaneously wide dynamic range (>20dB) and high resolution (<10cm). In this work, we develop and present a technique we refer to as Optical Side Scattering Radiometry (OSSR) capable of resolving discrete and distributed scattering properties of fibers along their length with up to 60dB dynamic range and 5cm spatial resolution. Our setup is first validated on a standard single mode telecoms fiber. Then we apply it to a record-length 11km hollow core photonic band-gap fiber (HC-PBGF) the characterization requirements of which lie far beyond the capability of standard optical reflectometric instruments. We next demonstrate use of the technique to investigate and explain the unusually high loss observed in another HC-PBGF and finally demonstrate its flexibility by measuring a HC-PBGF operating at a wavelength of 2µm. In all of these examples, good agreement between the OSSR measurements and other well-established (but more limited) characterization methods, i.e. cutback loss and OTDR, was obtained.

X-ray tomography for structural analysis of microstructured and multimaterial optical fibers and preforms.

Specialty optical fibers, in particular microstructured and multi-material optical fibers, have complex geometry in terms of structure and/or material composition. Their fabrication, although rapidly developing, is still at a very early stage of development compared with conventional optical fibers. Structural characterization of these fibers during every step of their multi-stage fabrication process is paramount to optimize the fiber-drawing process. The complexity of these fibers restricts the use of conventional refractometry and microscopy techniques to determine their structural and material composition. Here we present, to the best of our knowledge, the first nondestructive structural and material investigation of specialty optical fibers using X-ray computed tomography (CT) methods, not achievable using other techniques. Recent advances in X-ray CT techniques allow the examination of optical fibers and their preforms with sub-micron resolution while preserving the specimen for onward processing and use. In this work, we study some of the most challenging specialty optical fibers and their preforms. We analyze a hollow core photonic band gap fiber and its preforms, and bond quality at the joint between two fusion-spliced hollow core fibers. Additionally, we studied a multi-element optical fiber and a metal incorporated dual suspended-core optical fiber. The application of X-ray CT can be extended to almost all optical fiber types, preforms and devices.

Demonstration of amplified data transmission at 2 µm in a low-loss wide bandwidth hollow core photonic bandgap fiber.

The first demonstration of a hollow core photonic bandgap fiber (HC-PBGF) suitable for high-rate data transmission in the 2 µm waveband is presented. The fiber has a record low loss for this wavelength region (4.5 dB/km at 1980 nm) and a >150 nm wide surface-mode-free transmission window at the center of the bandgap. Detailed analysis of the optical modes and their propagation along the fiber, carried out using a time-of-flight technique in conjunction with spatially and spectrally resolved (S2) imaging, provides clear evidence that the HC-PBGF can be operated as quasi-single mode even though it supports up to four mode groups. Through the use of a custom built Thulium doped fiber amplifier with gain bandwidth closely matched to the fiber's low loss window, error-free 8 Gbit/s transmission in an optically amplified data channel at 2008 nm over 290 m of 19 cell HC-PBGF is reported.

Risk assessment in the face of a changing environment: gypsy moth and climate change in Utah.

The importance of efficaciously assessing the risk for introduction and establishment of pest species is an increasingly important ecological and economic issue. Evaluation of climate is fundamental to determining the potential success of an introduced or invasive insect pest. However, evaluating climatic suitability poses substantial difficulties; climate can be measured and assessed in a bewildering array of ways. Some physiological filter, in essence a lens that focuses climate through the requirements and constraints of a potential pest introduction, is required. Difficulties in assessing climate suitability are further exacerbated by the effects of climate change. Gypsy moth (Lymantria dispar L.) is an exotic, tree-defoliating insect that is frequently introduced into the western United States. In spite of an abundance of potential host species, these introductions have yet to result in established populations. The success of eradication efforts and the unsuccessful establishment of many detected and undetected introductions may be related to an inhospitable climate. Climatic suitability for gypsy moth in the western United States, however, is potentially improving, perhaps rapidly, due to a general warming trend that began in the mid 1970s and continues today. In this work, we describe the application of a physiologically based climate suitability model for evaluating risk of gypsy moth establishment on a landscape level. Development of this risk assessment system first required amassing databases that integrated the gypsy moth climatic assessment model, with host species distributions, and climate (historical, present, and future). This integrated system was then used to evaluate climate change scenarios for native host species in Utah, with the result that risk of establishment will dramatically increase during the remainder of the 21st century under reasonable climate change scenarios. We then applied the risk assessment system to several case histories of detected gypsy moth introductions in Utah. These applications demonstrated the general utility of the system for predicting risk of establishment and for designing improved risk detection strategies.

Warfarin interaction with erythromycin.

The drug interaction between warfarin and erythromycin is not well known. We report a case in which erythromycin was observed to markedly potentiate warfarin anticoagulation, resulting in hemorrhage in a patient treated for Legionella pneumonia. The morbidity of this drug interaction is enhanced in elderly patients who have infection accompanied by anorexia and/or fever and who are receiving intravenous erythromycin. The well-documented, temporal relationship established erythromycin as the interacting drug.

Electrophysiologic properties of perhexiline.

Perhexiline maleate (Pexid), a promising clinical antiarrhythmic and antianginal drug, was evaluated for its electrophysiologic effects on the entire conduction system of the intact canine heart throughout a wide range of therapeutic and potentially toxic doses. Intracardiac conduction times were measured by bipolar intramyocardial and transvenous endocardial electrodes before and following the intravenous administration of each dose of perhexiline maleate, 3 mg/kg every 30 min for a total of 4 doses in 7 open-chest anesthetized dogs. Eight animals served as controls in which similar operative technique and electrophysiologic variables were recorded after infusion of the maleate diluent. In addition, the effects of perhexiline on atrial and ventricular thresholds to electrical stimulation were recorded, as well as the QRS and QT intervals, sinus rate, and rhythm disorders. It was observed that perhexiline did not significantly (p greater than .05) alter sinus rate, QT interval, QRS duration, PR interval, intra-atrial conduction time, atrioventricular nodal conduction time, and His-Purkinje conduction velocity. The drug did not affect the cardiac threshold to electrical stimulation of less than 0.1 ma. No ectopic atrial or ventricular activity emerged during the accumulated influence of the agent. From this study, it is concluded that perhexiline does not exert deleterious actions on the conduction system of the intact canine heart. In view of the negligible toxic effects and its efficacy in treating ventricular tachyarrhythmias in patients, the drug deserves further clinical evaluation.

Combined diuretic and sympatholytic therapy in elderly patients with predominant systolic hypertension.

It has been speculated that the convenience and palatability of low-dose combination antihypertension treatment might enhance therapeutic effectiveness and compliance, especially in elderly patients. To test this possibility, patients over 60 years of age with predominant systolic hypertension were treated with a combination of a diuretic, chlorthalidone, and the centrally acting inhibitor of sympathetic activity, clonidine. The results of active treatment in these patients (n = 13) were compared with those of a placebo (n = 11). Active therapy with low doses of chlorthalidone and clonidine (usually once daily) controlled blood pressure (systolic pressure less than 140 mm Hg) in 12 of the 13 patients without inducing orthostatic hypotension. Administration of placebo did not result in significant changes in blood pressure. The diuretic-clonidine combination induced only small decreases in serum potassium levels and small increases in uric acid; no significant changes in creatinine clearance were observed. Both active and placebo therapy were tolerated without significant side effects. This study reveals that combined therapy with low doses of chlorthalidone and clonidine is effective, convenient, and palatable in controlling blood pressure in elderly patients with predominant systolic hypertension and supports the idea that treatment with sympathoinhibitory and volume-depleting agents is appropriate for this form of hypertension.

Treatment of gynecomastia with tamoxifen: a double-blind crossover study.

Benign asymptomatic or painful enlargement of the male breast is a common problem, postulated to be due to an increased estrogen/testosterone ration or due to increased estrogenic or decreased androgenic stimulation via estrogen or androgen receptor interactions. Treatment at present consists of analgesic medication or surgery. However, treatment directed against the preponderance of estrogenic stimulation would seem to represent a more specific form of therapy. In the present double-blind crossover study, one-month courses of a placebo or the antiestrogen tamoxifen (10 mg given orally bid) were compared in random order. Seven of ten patients experienced a decrease in the size of their gynecomastia due to tamoxifen (P less than 0.005). Overall, the decrease for gynecomastia for the whole group was significant (P less than 0.01). There was no beneficial effect of placebo (P greater than 0.1). Additionally, all four patients with painful gynecomastia experienced symptomatic relief. There was no toxicity. The reduction of breast size was partial and may indicate the need for a longer course of therapy. A followup examination was performed in eight out of ten patients nine months to one year after discontinuing placebo and tamoxifen. There were no significant changes from the end of the initial study period except for one tamoxifen responder who developed a recurrence of breast tenderness after six months, and one nonresponder who demonstrated an increase in breast size and a new onset of tenderness after ten months. Therefore, antiestrogenic treatment with tamoxifen may represent a safe and effective mode of treatment for selected cases of cosmetically disturbing or painful gynecomastia.

Effect of pharmaceutical care on optimum colestipol treatment in elderly hypercholesterolemic veterans.

We conducted a prospective trial to determine whether a formal, integrated pharmaceutical care plan can enhance patient acceptance and compliance with colestipol therapy and improve outcomes. Forty patients with hypercholesterolemia were equally divided and assigned to either a usual care or pharmaceutical care group. In the pharmaceutical care group compared with the usual care group, after 52 weeks, colestipol therapy resulted in a greater reduction in total cholesterol (12.5% vs 7.3%), low-density lipoprotein cholesterol (LDL-C; 16% vs 9.4%), and LDL-C:high-density lipoprotein cholesterol (HDL-C) ratio (24.4% vs 12.2%, p < 0.05). The percentage of patients who achieved their LDL-C goal at week 52 was much greater in the pharmaceutical care group (29.4%) than in the usual care group (5.0%, p < 0.05). Co-management by a physician and a pharmacist of hypercholesterolemic veterans treated with colestipol can enhance patient acceptance of the drug, LDL-C reduction, and achievement of therapeutic goals.

Fish oil as an adjuvant in the treatment of hypertension.

STUDY OBJECTIVE: To evaluate the effects of omega-3 fatty acids on blood pressure control and lipid levels. DESIGN: Double-blind, placebo-controlled, randomized study. SETTING: Veterans Affairs Medical Center teaching hospital. PATIENTS: Twenty-one men whose blood pressure was not optimally controlled with antihypertensive agents, who met the inclusion criteria. INTERVENTIONS: Patients were randomized to receive either fish oil (4.5 g omega-3 fatty acids/day) or placebo. MEASUREMENTS AND MAIN RESULTS: Blood pressure readings were taken at baseline, and 4 and 8 weeks. Sitting systolic and diastolic blood pressures were significantly reduced in the fish oil group at both week 4 (148/97 to 132/90, p <0.05) and week 8 (148/97 to 134/91, p <0.05). Sitting diastolic blood pressure was significantly reduced in the placebo group at week 8 (94 to 88, p <0.05). There was no difference in percentage change of sitting systolic and diastolic pressures at week 8 comparing the placebo group (-6.4% and -6.3%, respectively) and the fish oil group (-8.8% and -6.6%, respectively). Triglyceride levels (-40.9%, p <0.05) and platelet counts (-8.7%, p <0.05) were significantly reduced at 4 weeks, and low-density lipoprotein (LDL) cholesterol levels were significantly increased both at 4 and 8 weeks (13.5% and 19.1%, respectively) in the fish oil group. CONCLUSION: Adjunctive fish oil supplementation did not substantially augment blood pressure lowering in treated hypertensive men with suboptimally controlled blood pressure. Effects on plasma lipid values were mixed, with an increase in LDL cholesterol and a decrease in plasma triglyceride levels.

Impact of therapeutic interchange from pravastatin to lovastatin in a Veterans Affairs Medical Center.

OBJECTIVE: To evaluate the impact of a therapeutic interchange from pravastatin to lovastatin on treatment outcomes, quality of life, patient satisfaction, and costs. STUDY DESIGN: A prospective cohort study of 170 patients switched from pravastatin to lovastatin from September 1997 through November 1997. PATIENTS AND METHODS: The therapeutic interchange program promoting lovastatin as the preferred agent went into effect June 2, 1997 after Merck & Co. was awarded the Veterans Health Administration national contract for 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors. Patients were switched to lovastatin by either their primary care physician during routine clinic visits or the pharmacist by mail. The following outcomes were measured before and after conversion to lovastatin: lipid values, liver function tests, National Cholesterol Education Program (NCEP) low-density cholesterol (LDL-C) goals achieved, quality of life (QOL) (measured by the Medical Outcomes Study 36-item short-form health survey [SF-36]), medication tolerance (measured with a global symptom survey), patient satisfaction, and cost-minimization analysis. RESULTS: Lipid values and liver function test results were similar for pravastatin and lovastatin treatment. Forty percent of patients achieved NCEP LDL-C goals before and after formulary conversion. There were no significant differences between pravastatin and lovastatin in QOL, medication tolerance, and patient satisfaction. The projected cost savings from this therapeutic interchange was approximately $211,000 annually. CONCLUSION: Therapeutic interchange from pravastatin to lovastatin resulted in substantial cost savings. QOL, patient satisfaction, and achievement of NCEP LDL-C goals were maintained.

Lower limb ischaemia in the octogenarian: is limb salvage surgery worthwhile?

Vascular surgeons are being asked to manage vascular disease in an increasingly elderly population, and advanced age may be considered a relative contraindication to limb salvage surgery with an amputation seeming the preferred option. We present a review of 50 patients over the age of 80 years, presenting with ischaemic rest pain, ulceration or gangrene of the lower extremity. Six patients were treated conservatively, four of whom died during the same admission. Only two patients proved suitable for transluminal angioplasty as the sole curative procedure. Twelve patients (24%) underwent primary amputation with a perioperative mortality of 3/12 (25%). Five patients (10%) had an iliac bypass procedure, and 25 patients (50%) were considered suitable for infrainguinal bypass. Of the latter group 14 had femoropopliteal bypasses, and 11 had femorodistal bypasses with an overall perioperative mortality of 3/25 (12%). Mortality at 6 months was high (33%) and was similar in both the grafted and amputation groups. Patients having reconstruction fared well in terms of independent mobility, use of long-term care, and length of hospital stay. Patients over 80 years of age with critical ischaemia should not be denied the opportunity of vascular reconstruction.

Documentation and assessment of pharmacist-initiated drug therapy interventions.

In conclusion, the development of an efficient system to document pharmacist-initiated drug therapy interventions has been successful. The system has been incorporated into the pharmacy quality assurance program and is being used to evaluate the provision of pharmaceutical care. Finally, the system has been incorporated into the clinical services drug-use evaluation program and is being used to evaluate individual physician prescribing practices.

Promotion of extended-release niacin tablets at a Veterans Affairs medical center.

A program to modify the prescribing of antilipemic agents by promoting the use of extended-release niacin tablets is described. Between December 1987 and August 1988, pharmacists at a 1188-bed Veterans Affairs medical center observed a large increase in the number of outpatient prescriptions for antilipemic agents. In an attempt to control costs, a program to promote the use of extended-release niacin tablets for treating hyperlipemia was conducted during August and September 1988. Various educational materials on niacin were distributed to physicians. A display on therapy of hyperlipemia was featured at the monthly drug fair, and articles on niacin were presented during a journal club meeting of ambulatory-care clinicians. Pharmacists succeeded in having extended-release niacin tablets placed on the formulary in September. Data on the number of prescriptions filled for antilipemic agents were collected before and after the niacin promotional program. The number of prescriptions filled for extended-release niacin 500-mg tablets increased steadily during a six-month study period after the program ended; the number of prescriptions filled for regular niacin decreased by 50%. As prescribing of extended-release niacin increased, prescribing of colestipol, gemfibrozil, and probucol declined. The promotional program was well received by most of the medical staff. A program of education and formulary management successfully changed physician prescribing habits for antilipemic agents.

Chlorpropamide-induced hyponatremia in the veteran population.

OBJECTIVE: To determine the incidence and possible risk factors associated with chlorpropamide (CPA)-induced hyponatremia in the veteran population. DESIGN: Retrospective cohort study. SETTING: Federal tertiary care medical center. PATIENTS: Veterans receiving CPA from our facility with at least one serum sodium concentration below 135 mmol/L within the past year were eligible. A randomly selected control group consisting of patients taking CPA with normal sodium concentrations was also chosen. One hundred forty-five of 799 patients who had received CPA were included in the study. RESULTS: The average daily dose of CPA was 425 +/- 207 mg (+/- SD). The incidence of hyponatremia associated with CPA was 7.1 percent (57/799 patients). The majority of patients were mildly hyponatremic (48/57 patients, 84 percent) with serum sodium concentrations between 130 and 134 mmol/L. The incidence of CPA-induced syndrome of inappropriate antidiuretic hormone was 2.1 percent. Concurrent angiotensin-converting enzyme (ACE) inhibitor use was identified as a risk factor; thiazide diuretic use was not. CONCLUSIONS: The incidence of hyponatremia related to CPA use in elderly veterans is consistent with other reports in the literature. ACE inhibitors may be a predisposing factor for CPA-induced hyponatremia.

Physical child abuse: a review of all cases seen at Sacramento Medical Center in 1975.

This report presents physical, socioeconomic, demographic and follow-up information on all 18 cases of physical child abuse seen at the Sacramento Medical Center in 1975. Of the 18 abused children, 16 were initially discharged to Children's Protective Service; 13 were placed in foster homes. There were 17 alleged abusers; all were arrested; 12 came to trial; 8 were convicted. Preventive programs offer a less expensive approach and deserve the highest priority.

Gentamicin bioavailability and single-dose pharmacokinetics in spinal cord injury.

The rate and completeness of absorption of gentamicin from muscle (healthy and paralyzed) and gentamicin disposition kinetics following a single intravenous infusion were studied in nonobese, healthy male volunteers with functionally complete, chronic (greater than one year duration) spinal cord injury (SCI) and in able-bodied controls. Pharmacokinetic parameters were derived using compartmental and model-independent analyses. The absolute bioavailability of gentamicin was complete and did not differ from control values using both model-independent (LAGRAN) and model-dependent (ADAPT) analyses. The rate of gentamicin absorption in patients with SCI was, however, significantly slower, with a mean absorption time of 2.55 h compared with 0.96 h in able-bodied controls (p less than or equal to 0.05). Mean volume of distribution steady-state (Vssd) of gentamicin was demonstrated to be 33-47 percent greater in spinal cord injury than in controls (p less than 0.05). We conclude that the absorption of gentamicin from paralyzed muscle is significantly impaired, and in conjunction with an increase in Vssd results in delayed, decreased peak serum levels in patients with SCI.

Effects of low-dose antihypertensive therapy in elderly patients with predominant systolic hypertension.

Patients over 60 years of age (M = 70 years) with the predominant systolic form of essential hypertension (systolic blood pressure greater than 160 mm Hg; diastolic blood pressure less than 100 mm Hg) were treated with a combination of low doses of the diuretic chlorthalidone and the centrally-acting sympatholytic agent clonidine. In this randomized double-blind study, patients received either active treatment (n = 14) or placebo (n = 16). Baseline systolic blood pressure in the treatment group averaged 172 mm Hg and was controlled (fall in systolic blood pressure to less than 140 mm Hg or by at least 10%) in 13 of the 14 patients; in eight patients, control was achieved with a single daily dose (given at night) of the clonidine (.1 mg)-chlorthalidone (15 mg) combination. The active drug was significantly superior to placebo in decreasing systolic blood pressure. Changes measured in the standing position did not differ from those in the supine position. Side effects were mild and transient for both the placebo and the treatment groups. Low-dose combination therapy appears to be a highly effective approach for the management of older patients with predominant systolic hypertension of mild-to-moderate degree.