Initial Rapid Fall Research Articles

Population Pharmacokinetic Modelling of Intravenous Immunoglobulin Treatment in Patients with Guillain-Barré Syndrome.

Background and ObjectiveIntravenous immunoglobulin (IVIg) at a standard dosage is the treatment of choice for Guillain–Barré syndrome. The pharmacokinetics, however, is highly variable between patients, and a rapid clearance of IVIg is associated with poor recovery. We aimed to develop a model to predict the pharmacokinetics of a standard 5-day IVIg course (0.4 g/kg/day) in patients with Guillain–Barré syndrome.MethodsNon-linear mixed-effects modelling software (NONMEM®) was used to construct a pharmacokinetic model based on a model-building cohort of 177 patients with Guillain–Barré syndrome, with a total of 589 sequential serum samples tested for total immunoglobulin G (IgG) levels, and evaluated on an independent validation cohort that consisted of 177 patients with Guillain–Barré syndrome with 689 sequential serum samples.ResultsThe final two-compartment model accurately described the daily increment in serum IgG levels during a standard IVIg course; the initial rapid fall and then a gradual decline to steady-state levels thereafter. The covariates that increased IgG clearance were a more severe disease (as indicated by the Guillain–Barré syndrome disability score) and concomitant methylprednisolone treatment. When the current dosing regimen was simulated, the percentage of patients who reached a target ∆IgG > 7.3 g/L at 2 weeks decreased from 74% in mildly affected patients to only 33% in the most severely affected and mechanically ventilated patients (Guillain–Barré syndrome disability score of 5).ConclusionsThis is the first population-pharmacokinetic model for standard IVIg treatment in Guillain–Barré syndrome. The model provides a new tool to predict the pharmacokinetics of alternative regimens of IVIg in Guillain–Barré syndrome to design future trials and personalise treatment.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40262-022-01136-z.

Safety, hemodynamic effects, and detection of acute xenon inhalation: rationale for banning xenon from sport.

This study aimed to quantify the sedative effects, detection rates, and cardiovascular responses to xenon. On 3 occasions, participants breathed xenon (FiXe 30% for 20 min; FiXe 50% for 5 min; FiXe 70% for 2 min) in a nonblinded design. Sedation was monitored by a board-certified anesthesiologist. During 70% xenon, participants were also verbally instructed to operate a manual value with time-to-task failure being recorded. Beat-by-beat hemodynamics were measured continuously by ECG, photoplethysmography, and transcranial Doppler. Over 48 h postadministration, xenon was measured in blood and urine by gas chromatography-mass spectrometry. Xenon caused variable levels of sedation and restlessness. Task failure of the self-operating value occurred at 60-90 s in most individuals. Over the first minute, 50% and 70% xenon caused a substantial reduction in total peripheral resistance (P < 0.05). All dosages caused an increase in cardiac output (P < 0.05). By the end of xenon inhalation, slight hypertension was observed after all three doses (P < 0.05), with an increase in middle cerebral artery velocity (P < 0.05). Xenon was consistently detected, albeit in trace amounts, up to 3 h after all three doses of xenon inhalation in blood and urine with variable results thereafter. Xenon inhalation caused sedation incompatible with self-operation of a breathing apparatus, thus causing a potential life-threatening condition in the absence of an anesthesiologist. Yet, xenon can only be reliably detected in blood and urine up to 3 h postacute dosing.NEW & NOTEWORTHY Breathing xenon in dosages conceivable for doping purposes (FiXe 30% for 20 min; FiXe 50% for 5 min; FiXe 70% for 2 min) causes an initial rapid fall in total peripheral resistance with tachycardia and thereafter a mild hypertension with elevated middle cerebral artery velocity. These dose duration intervals cause sedation that is incompatible with operating a breathing apparatus and can only be detected in blood and urine samples with a high probability for up to ~3 h.

Effects of Grain Size on Mechanical Properties and Work‐Hardening Behavior of AISI 304 Austenitic Stainless Steel

Grain size effects on the properties of AISI 304 austenitic stainless steel are studied. Yield stress (YS) and ultimate tensile strength (UTS) increased with decreasing grain size (Hall–Petch law) while the difference between YS and UTS decreased. Three distinct stages for work‐hardening rate are identified: I) initial rapid fall until reaching a minimum value, II) subsequent rise to a maximum due to the transformation‐induced plasticity (TRIP) effect, which is found to enhance by increasing grain size, and III) final fall until the onset of necking. More in‐depth analysis on the mechanical stability of austenite reveals that for below‐average grain size of ≈50 μm, by decreasing grain size, the TRIP effect diminishes; whereas for grain size larger than ≈50 μm, by increasing grain size, the TRIP effect becomes less pronounced. Due to the strong TRIP effect, high incremental work‐hardening exponents (n‐values of higher than 0.8) and low‐yield ratios (smaller than 0.5) are observed. It is also found that when the average grain size increases, the tensile toughness and the size and depth of dimples increase. The latter is responsible for the tardiness of the microcavity coalescence, which is indicative of high ductility of this austenitic alloy.

Reinterpretation of the Tension Response of Muscle to Stretches and Releases

We have reexamined the experimental time courses of tension in frog muscle after rapid length steps. The early tension recoveries are biexponential. After 3 nm/hs stretches and releases, the rates of the immediate rapid tension changes are similar but the subsequent tension fall after a stretch is much slower than the rise after a release. After 1.5 nm/hs length steps, the entire tension responses are more nearly mirror images. To identify the underlying processes, we used a model of the muscle cross-bridge cycle with two tension-generating (tensing) steps. Analysis of the time course of the tension, the rates of the steps in the cycle, and their contributions to tension provided insights into previously puzzling features of the experimental response. After a stretch, the initial rapid tension fall in the model is caused principally by the reversal of the first tensing step, but after a few milliseconds the tensing step resumes its forward direction. We conclude that the remaining response should not be included in phase 2, the period of early tension recovery. With this exclusion, T2, the tension at the end of this period, rises with an increase of stretch. The rate of early tension recovery also increases with stretch size, showing that the reversal of the first tensing step is strain sensitive. After small length steps, the fast and slow components of the early tension recovery are both caused mainly by the first tensing step. The fast component is triggered by the initial sliding of the filaments, and the slow component is due to further sliding that occurs as the tension recovers. With small length steps (<0.5 nm/hs), the time course of the response to a stretch is the reverse of that to a release.

Fertility, Marriage, and Family Planning in Iran: Implications for Future Policy

Abstract The Islamic Republic of Iran has experienced a remarkable demographic transition over the last three decades. As a result of social, demographic and economic changes, Iran’s fertility declined from 7.0 births per woman in 1980 to around 1.8 to 2.0 in 2011 based on our estimation (McDonald et al. 2015). The initial rise and rapid fall of fertility accompanied by a decline of child mortality led to a post-revolutionary youth bulge in the age distribution that will lead to rapid ageing in the longer-term future. Others have argued that Iran’s fertility has fallen to much lower levels - as low as 1.5 births per woman (eg. Erfani 2013). Such low estimates led to the Government of Iran adopting a pronatalist policy with the aim of increasing fertility, although the components of the policy are still under discussion. Different views have been expressed on the role of family planning and other programs in meeting population policy goals in Iran in the future with some advocating the discontinuation of government assistance to family planning. This paper aims to review the trends and levels of fertility, marriage, and family planning and their implications for policy. Using various datasets and detailed parity-based measures of fertility, the dynamics of fertility regulation practiced by Iranian couples are investigated. Our findings suggest that contraceptive use stabilized before 2000 and postponement of the first child and wide birth intervals are the main contributors to the level of fertility. Therefore, instead of discontinuation of the family planning program, policy to sustain fertility at its present level or a little higher needs to focus upon improving the economic circumstances of young people so that they are able to make less constrained choices about family formation than is the case at present.

Sustained sympathetic nervous system support of arterial blood pressure during repeated brief umbilical cord occlusions in near-term fetal sheep

Sympathetic nervous system (SNS)-mediated peripheral vasoconstriction plays a key role in initial maintenance of blood pressure during rapid-onset asphyxia in the mammalian fetus, but it is attenuated after the first few minutes. It is unclear whether the SNS response is sustained during the brief, but frequently repeated, episodes of asphyxia characteristic of labor. In the present study, 14 fetal sheep at 0.85 of gestation received either chemical sympathectomy with 6-hydroxydopamine (6-OHDA; n = 7) or sham injection (control; n = 7), followed 4-5 days later by repeated 2-min episodes of complete umbilical cord occlusion every 5 min for up to 4 h or until mean arterial blood pressure (MAP) fell to <20 mmHg for two successive occlusions. In controls, umbilical cord occlusions were associated with a rapid initial fall in fetal heart rate (FHR) and femoral blood flow (FBF), with initial hypertension, followed by progressive development of hypotension during ongoing occlusions. Sympathectomy was associated with attenuation of the initial rise in MAP during umbilical cord occlusion, and after the onset of hypotension, a markedly more rapid fall of MAP to the nadir, with a correspondingly slower fall in FBF (P < 0.05). In contrast, MAP and FHR between successive occlusions were higher after sympathectomy (P < 0.05). There was no significant difference in the number of occlusions before terminal hypotension (6-OHDA; 16.1 ± 2.2 vs. control; 18.7 ± 2.3). These data show that SNS activity provides ongoing support for fetal MAP during prolonged exposure to brief repeated asphyxia.

Dynamic response of a fish swim bladder to transient sound

High-level underwater sound exposures from impact pile driving activities and seismic air guns can cause physical damage to fishes. Damage to biological tissues depends on the strain rate induced by the initial rapid rise and fall times of the received sound pulse. So a time-domain analysis is needed to understand mechanisms of tissue damage resulting from exposure to sound from transient acoustic sources. To address this issue, the frequency domain mathematical model originally developed by Finneran and Hastings (JASA 108: 1308-1321, 2000) was modified to predict the response of a fish swim bladder and surrounding tissues to transient signals. Each swim bladder chamber was modeled as an elastic prolate spheroidal shell filled with gas and connected to other parts of the anatomy. Results of three case studies are presented showing correlation between the strain rate of the swim bladder wall and tissue damage reported in five different species of fish.

Do Different Glucose Levels at Calibration Influence Accuracy of Continuous Glucose Monitoring Readings in Vitro?

Two limitations shared by all continuous glucose monitors (CGMs) are poor accuracy in the hypoglycemic range1 and poor accuracy when glycemia is changing rapidly.2 This raises the issue of whether aspects of the calibration procedure could improve sensor accuracy in the hypoglycemic range. Retrospective analysis of CGM readings using in silico (i.e., computer-based) modeling suggest that the glucose levels at which calibrations are performed affect the performance of CGMs.3–5 The purpose of this study was to determine whether the intrinsic accuracy per se of CGMs also improves in the low glucose range if multiple calibrations are performed at different and low glucose concentrations in vitro. Twelve sensors (Sof-sensor®; Medtronic, Northridge, CA) were exposed to three calibration conditions using Paradigm® 722 REAL-Time CGMs (Medtronic, Northridge, CA) following a randomized counterbalanced design. Each CGM was calibrated and tested in glucose solutions prepared in a Krebs physiological bicarbonate buffer at 37 °C and pH of 7.4. Since Paradigm 722 REAL-Time CGM units must be calibrated four times daily, with several calibration points rather than only the most recent calibration value being used for calibration, each unit was calibrated four times in a 144 mg/dl solution (144/144/144/144 mg/dl) or calibrated four times in 72, 144, or 216 mg/dl solutions following the sequence 144/72/216/144 mg/dl or 144/216/72/144 mg/dl, with a 40 min period between each calibration. Then, the units were tested by transferring the sensors to a 40-mg/dl solution and data compared when glucose readings reached stable levels. A one-way analysis of variance with repeated measures and Bonferroni post-hoc tests were adopted to compare calibration protocols (results expressed as mean ± standard error of the mean, p 0.05). There were also large mismatches between the CGM and reference glucose associated with the CGM’s lag, most notably during the initial rapid fall in glucose levels (5–15 min; Figure 1) but no differences in the magnitude of these mismatches between calibration protocols at 5, 10, and 15 min as well as with the lag time defined as the time required for CGM glucose readings to decrease by half of the absolute change in reference glucose concentration (Figure 1; p > 0.05). However, since the glucose level of the last calibration solution was matched for all calibration protocols, we examined whether different glucose levels at the last calibration step affect accuracy and found that CGMs calibrated at 72 mg/dl misread the 40 mg/dl solution to a lesser extent (3.6 ± 1.8 mg/dl) compared to CGMs calibrated at 144 mg/dl (12.6 ± 1.8 mg/dl; p < 0.05) and 216 mg/dl (16.2 ± 1.8 mg/dl; p < 0.05). This indicates that the accuracy of the CGM tested here was influenced by the glucose level at which the last calibration was performed, thus corroborating, in part, the findings based on computer-based modeling.3–5 However, given the evidence that CGM performance in vivo is poorer than in vitro,6 it remains to be tested whether calibration at different glucose levels might be even more beneficial in vivo than reported here in vitro. Figure 1 Effect of calibration protocol on CGM glucose measurements during an immediate fall in glucose concentration (from a 144 to 40 mg/dl solution). Repeated calibration at 144/144/144/144 mg/dl (□), 144/72/216/144 mg/dl (Δ), or 144/216/72/144 ...

The rate of recovery of cardiac function after cardiac arrest: A theoretical study

Introduction: During a cardiac arrest there is an initial rapid fall in arterial pressure followed by a more gradual decline until arterial and venous pressures equalize. This is accompanied by distension of the right ventricle and compression of the left ventricular cavity. The aims of this study were to develop a mathematical model of the circulation to simulate a cardiac arrest and to investigate the relative importance of fluid shifts in the circulation and ischaemia on the rate of recovery of blood pressure post-arrest.

Effect of extensional cyclic strain on the mechanical and physico-mechanical properties of PVC-NBR/graphite composites

The variation of electrical resistivity as will as the mechanical properties of PVC (polyvinylchloride)-NBR (acrylonitrile butadiene rubber) based conductive composites filled with different concentrations of graphite were studied. These samples were studied as function of the constant deformation fatigue test. When the specimen was subjected to a large number of rapidly repeating strain cycles, and different strain amplitudes, the conductivity, σ(T), shows an initial rapid fall followed by dynamic equilibrium. Increasing the number of cycles and strain amplitudes, the conductivity remains almost constant over the temperature range 30-140°C. The equilibrium state between destruction and reconstruc- tion of graphite particles has been detected for all strains of certain values of strain cycles (1000, 2000, 3000, and 4000 cycles for 30% strain amplitude). A preliminary study was done to optimize the possibility to use Conductive Polymer Composites (CPC) as a strain sensor and to evaluate its performance by an intrinsic physico-mechanical modification meas- urement. The electromechanical characterization was performed to demonstrate the adaptability and the correct functioning of the sensor as a strain gauge on the fabric. The coefficient of strain sensitivity (K) was measured for 50 phr graphite/PVC- NBR vulcanized at 3000 number of strain cycles and 30% strain amplitude. There was a broad maximum of K, with a peak value of 82, which was much higher, compared to conventional wire resistors. A slight hysteresis was observed at unload- ing due to plasticity of the matrix. A good correlation exists between mechanical and electrical response to the strain sensi- tivity. Mechanical reinforcement was in accordance with the Quemada equation (1) and Guth model (2) attested to good particle-matrix adhesion. It was found that the viscous component of deformation gradually disappeared and the hardening occurred with increasing strain cycles. The modulus, fracture strength, and elongation at break increased with increasing filler volume fraction up to 40 phr of graphite particles.

Preexisting hypoxia is associated with a delayed but more sustained rise in T/QRS ratio during prolonged umbilical cord occlusion in near-term fetal sheep

There is limited information about whether preexisting fetal hypoxia alters hemodynamic responses and changes in T/QRS ratio and ST waveform shape during subsequent severe asphyxia. Chronically instrumented near-term sheep fetuses (124 +/- 1 days) were identified as either normoxic Pa(O(2)) > 17 mmHg (n = 9) or hypoxic Pa(O(2)) < or = 17 mmHg (n = 5); then they received complete occlusion of the umbilical cord for 15 min. Umbilical cord occlusion led to sustained bradycardia, severe acidosis, and transient hypertension followed by profound hypotension in both groups. Preexisting hypoxia did not affect changes in mean arterial blood pressure but was associated with a more rapid initial fall in femoral blood flow and vascular conductance and with transiently higher fetal heart rate at 2 min and from 9 to 11 min of occlusion compared with previously normoxic fetuses. Occlusion was associated with a significant but transient rise in T/QRS ratio; preexisting hypoxia was associated with a significant delay in this rise (maxima 3.7 +/- 0.4 vs. 6.2 +/- 0.5 min), but a slower rate of fall. There was a similar elevation in troponin-T levels 6 h after occlusion in the two groups [median (range) 0.43 (0.08, 1.32) vs. 0.55 (0.16, 2.32) microg/l, not significant]. In conclusion, mild preexisting hypoxia in normally grown singleton fetal sheep is associated with more rapid centralization of circulation after umbilical cord occlusion and delayed elevation of the ST waveform and slower fall, suggesting that chronic hypoxia alters myocardial dynamics during asphyxia.

Hypoxic pulmonary vasoconstriction in intact rat intrapulmonary arteries is not initiated by inhibition of Na+-Ca2+ exchange

It has been proposed that a hypoxia-induced inhibition of the Na(+)-Ca(2+) exchanger (NCX) contributes to hypoxic pulmonary vasoconstriction (HPV). By recording isometric tension development in rat intrapulmonary arteries (IPA), we examined the effect on HPV of maneuvers that reduce the ability of NCX to regulate intracellular Ca(2+) concentration ([Ca(2+)](i)). In some experiments, fura pentakis(acetoxymethyl) ester-3 (fura PE-3) was also used to monitor [Ca(2+)](i). HPV was elicited in IPA that were pretreated with 10 microM diltiazem and slightly preconstricted with PGF(2alpha), which enhances the hypoxic response. Substitution of Na(+) with Li(+) increased HPV and the associated rise in [Ca(2+)](i). Pretreatment with ouabain (100 microM) to diminish the Na(+) gradient or with the reverse-mode NCX inhibitor KB-R7943 (3 or 10 microM) had no significant effect on HPV. Combined treatment with ouabain and low-[Na(+)] (24 mM) solution enhanced HPV strongly. The role of NCX in Ca(2+) extrusion was examined by assessing the decrease in [Ca(2+)](i) in Ca(2+)-free physiological saline solution either containing or lacking Na(+) following a high K(+)-induced loading of cellular [Ca(2+)]. Although the large initial rapid fall in [Ca(2+)] was Na(+) independent, final recovery of [Ca(2+)] to its basal level was delayed in the absence of Na(+). Therefore, HPV persisted or was increased under conditions in which forward-mode NCX was already attenuated or prevented, demonstrating that inhibition of NCX by hypoxia is unlikely to initiate HPV. Instead, NCX appears to act to inhibit HPV as would be expected if it is functioning to extrude Ca(2+).

Dielectric constant/loss measurements in pristine and 75 MeV oxygen-ion irradiated kapton-H polyimide

The dielectric constant (ϵ′) and loss factor (ϵ″) measurements have been made in pristine and 75 MeV oxygen-ion irradiated (fluences: 1.8×1011, 1.8×1012 and 1.8×1013 ions/cm2) kapton-H polyimide in the temperature region 20–240 °C at different frequencies ranging from 1 kHz–4 MHz. There is an overall decrease in ϵ′ in irradiated samples. The decrease in ϵ′ is more in samples irradiated with high fluences. In pristine kapton-H sample, the initial rapid fall in ϵ′ with temperature has been ascribed to the loss in absorbed water (γ-relaxation). The increase in crystallinity, dipolar relaxation (β-relaxation) and space charge relaxation (α-relaxation) governs the high temperature ϵ′. In irradiated samples, the ion irradiation results in an enhancement of γ-relaxation, which significantly affects the low-temperature ϵ′ behaviour. The decrease in ϵ′ with temperature above 40 °C has been associated with the demerization of carbonyl groups due to high-energy ion irradiation. In the high-temperature region (above 140 °C), the radiation induced free radical cross-linking has been held responsible for decreasing ϵ′ with temperature. The loss peaks in ϵ″–T curves appearing around 40–50, 80–120 and 140–180 °C represent the γ, β and α-relaxations, respectively.

Islet Cell Function Its Role in the Onset and Progression of Type 2 Diabetes

Studies of the natural history of type 2 diabetes have transformed views on the nature of the condition in the last two decades.The Belfast Study is one of the earliest and most complete studies to observe the change in blood glucose control during six years of best possible management by dietary means. After the rapid initial fall from presenting blood glucose levels over 11mM, mean fasting blood glucose was maintained around 8mM for only two years before an inexorable rise occurred. By six years after diagnosis mean plasma glucose was over 10mM.This work is all the more impressive as no oral agent therapy was used during the course of the study which truly observed natural history modified only by consistent and expert dietary advice. Calculated beta cell function revealed a fall from around 30% of normal function at diagnosis to around 22% after six years.

Fetal acidosis and hypotension during repeated umbilical cord occlusions are associated with enhanced chemoreflex responses in near-term fetal sheep

This study examined the hypothesis that repeated episodes of brief but severe hypoxia would not attenuate the chemoreflex-mediated rapid initial fall in fetal heart rate (FHR) and, further, that greater hypoxic stress, as shown by hypotension and metabolic acidosis, would be associated with an enhanced chemoreflex response. Chronically instrumented, near-term fetal sheep received 1 min total umbilical cord occlusion either every 5 min for 4 h (1:5 group; n = 8) or every 2.5 min (1:2.5 group; n = 8) until mean arterial blood pressure fell to <20 mmHg on two successive occlusions. Umbilical cord occlusion caused variable decelerations, with sustained hypertension in the 1:5 group and little change in acid-base status (pH 7.34 +/- 0.03 after 4 h). In contrast, the 1:2.5 group showed progressive hypotension and metabolic acidemia (pH 6.92 +/- 0.04 after the last occlusion). The 1:2.5 group showed a significant increase in the rate of initial fall in FHR during the occlusion series, which was greater than the 1:5 group in the last 30 min of the occlusion series (9.4 +/- 1.4 vs. 3.5 +/- 0.3 beats.min(-1).s(-1); P < 0.01), with a greater fall in FHR (71.9 +/- 6.5 vs. 47.0 +/- 8.7 beats/min; P < 0.05). In summary, this study demonstrated that repetitive laborlike cord occlusions, which led to severe fetal compromise, were associated with an increase in the slope and magnitude of the initial FHR deceleration. These findings support the concept of the chemoreflex as a central, robust component of fetal adaptation to severe hypoxia.

Incidence and risk factors for immune reconstitution inflammatory syndrome during highly active antiretroviral therapy

There is little systematic information regarding the immune reconstitution inflammatory syndrome (IRIS). To determine the incidence, risk factors, and long-term outcome of IRIS in HIV-infected patients receiving highly active antiretroviral therapy (HAART) who were coinfected with one of three common opportunistic pathogens. A retrospective cohort identified through a city-wide prospective surveillance program. A retrospective chart review was performed for 180 HIV-infected patients who received HAART and were coinfected with Mycobacterium tuberculosis, Mycobacterium avium complex, or Cryptococcus neoformans between 1997 and 2000. Medical records were reviewed for baseline demographics, receipt and type of HAART, response to antiretroviral therapy, development of IRIS, and long-term outcome. In this cohort, 31.7% of patients who received HAART developed IRIS. Patients with IRIS were more likely to have initiated HAART nearer to the time of diagnosis of their opportunistic infection (P < 0.001), to have been antiretroviral naive at time of diagnosis of their opportunistic infection (P < 0.001), and to have a more rapid initial fall in HIV-1 RNA level in response to HAART (P < 0.001). IRIS is common among HIV-infected persons coinfected with M. tuberculosis, M. avium complex, or C. neoformans. Antiretroviral drug-naive patients who start HAART in close proximity to the diagnosis of an opportunistic infection and have a rapid decline in HIV-1 RNA level should be monitored for development of this disorder.

Starvation survival, growth and recovery of Enterococcus faecalis in human serum.

The ability of Enterococcus faecalis to survive starvation for long periods in the obturated root canal is likely to be an important factor in the pathogenesis and maintenance of a persistent infection after endodontic treatment. The response of E. faecalis to starvation survival in water and glucose-, phosphate- or amino acid-limited chemically defined medium was studied, along with the capacity for growth and recovery of starved cells of E. faecalis in pooled human serum. After an initial rapid fall in cell numbers, a small remaining population of E. faecalis was able to survive in water for over 4 months and in nutrient-limited media for extended periods. A high cell density at the onset of starvation was critical for the ability of E. faecalis to endure prolonged nutrient limitation. Upon starvation, a static population of starved cells developed and were apparently in a minimal metabolic state, since blocking cell wall synthesis with penicillin G or inhibiting DNA synthesis with norfloxacin during starvation resulted in limited change in the rate of loss of viable cells. In 50% serum, E. faecalis grew, then stabilized at a relatively constant population of 106 colony-forming units/ml for 4 months, irrespective of the initial cell density. In summary, E. faecalis is capable of withstanding prolonged periods of starvation in a minimal metabolic state provided that there is a high cell density at the onset of starvation. Starved cells were capable of recovery upon addition of human serum.

Effects of postannealing in ozone environment on opto-electrical properties of Sn-doped In 2O 3 thin films

Effects of postannealing on electrical, optical and chemical properties in Sn-doped In 2O 3 (ITO) thin films are studied in the case when the annealing is carried out in ozone-incorporated oxygen atmosphere [O 3]. The results are compared to the cases of annealing with the conventional reactive gases, pure oxygen [O 2] and ambient air [Air]. The ITO films were deposited by electron-beam evaporation on polyester at room temperature, followed by postannealing at 150 °C for annealing time up to 120 min. Evidence is obtained that the optical transmittance and resistivity of films can be improved more significantly in the order of [O 3]>[O 2]>[Air] upon annealing for 60 min, though the effects of [O 3] and [O 2] become comparable by further annealing. A rapid initial fall in the resistivity observed in the case of [O 3] is dominated by a large increment in carrier density, while the contribution from the carrier mobility becomes more evident for longer annealing time. The oxygen content relative to indium in the middle region of the films, determined from X-ray photoemission study, seems to be correlated with the behavior of the opto-electrical properties upon postannealing. The enhanced improvement of those properties by the ozone treatment could be attributed to its strong oxidizing ability.

The apparent late half-life of human chorionic gonadotropin (hCG) after surgical treatment for ectopic pregnancy: A new approach to diagnose persistent trophoblastic activity

Objective: The disappearance kinetic of human chorionic gonadotropin (hCG) follows a biexponential decay with a rapid initial fall followed later by a slow disappearance. This kinetic is characterised by two half-lives: an early and a late. The objective of this study was to determine if and which half-life could be used clinically to detect persistent trophoblast after conservative surgery in patients with ectopic pregnancy. Design: Retrospective analysis of patients having undergone salpingostomy by laparoscopy for an ectopic tubal pregnancy between January 1990 and October 1993. Setting: Gynaecology Department of an University Hospital. Patients: 104 women with diagnosed tubal ectopic pregnancy were treated by salpingostomy performed under laparoscopy. In seven cases, persistent trophoblast was diagnosed on the basis of plateauing or increasing peripheral hCG values. Main results: From the individual disappearance curves of hCG we calculated the early half-life (early T 0.5, from samples obtained between 0 and 48 h postsurgery) and the late half-life (late T 0.5, from samples obtained between 2 and 7 days postsurgery). Late T 0.5 but not early T 0.5 were significantly ( P<0.0001 and P=0.416 respectively) longer in women ( n=7) in whom a persistent trophoblast was diagnosed. Early T 0.5 was dependant on the preoperative value of hCG, whereas late T 0.5 was independent. We propose to use late T 0.5 as a parameter to follow ectopic pregnancies after treatment.

Angiotensin II and cardiovascular chemoreflex responses to acute hypoxia in late gestation fetal sheep.

1. In six intact and nine carotid sinus denervated (CSD) fetal sheep (125-128 days gestation) we measured heart rate (FHR), mean systemic arterial blood pressure (MAP), femoral and carotid blood flows (FBF and CBF), and femoral and carotid vascular resistances (FVR and CVR). Three experiments were conducted on successive days: normoxia followed by acute isocapnic hypoxia (Pa,O2 to ca 12 mmHg) with infusion of vehicle (HV experiment), the same protocol but with infusion of the angiotensin converting enzyme (ACE) inhibitor, captopril (HC experiment), and normoxia alone with captopril infusion (NC experiment). Plasma angiotensin II concentration ([AII]) was measured in these fetuses, and in a separate group of fetuses (n = 5) that were infused with the nitric oxide (NO) synthesis inhibitor N G-nitro-L-arginine methyl ester (L-NAME) or saline vehicle. 2. During normoxia, cardiovascular parameters and plasma [AII] were unaltered by captopril infusion, apart from a fall in MAP (NC experiment only, P < 0.05) and FHR (HC experiment only, P < 0.05) in intact and CSD fetuses, respectively. No differences were observed between intact and CSD groups. 3. At the onset of hypoxia the rapid initial fall in FHR and rise in FVR was attenuated in CSD fetuses. In all fetuses FHR returned towards prehypoxic levels as hypoxia continued. In contrast, during hypoxia with vehicle infusion (HV experiment) plasma [AII] rose to a similar level in intact and CSD fetuses. 4. In both intact and CSD fetuses, the rise in [AII] during hypoxia was blocked by captopril or L-NAME infusion. In CSD, but not intact, fetuses infused with captopril the rise in MAP was absent, and the fall in FBF and rise in FVR did not reach significance during hypoxia. 5. Thus, during normoxia CSD alone, or combined with ACE inhibition, does not consistently alter basal cardiovascular control in the late gestation fetus. The rise in [AII] during hypoxia is not mediated by carotid reflexes but may involve NO-dependent mechanisms. In intact fetuses, AII does not appear to be pivotal in cardiovascular control during hypoxia. It is only when carotid reflex mechanisms are removed that a role for AII in the regulation of MAP and peripheral blood flow during hypoxia becomes apparent. These findings lend weight to the idea of multiple mechanisms of fetal cardiovascular control during hypoxia.