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Antepartum fetal heart rate monitoring. III. Fetal movements and accelerations in fetal heart rate.

This third part of the paper deals with the study of the relationships between fetal movements, fetal heart rate accelerations associated with such movements, fetal heart rate instability and neonatal outcome. No correlations has been found between absence of fetal movements and neonatal distress. A correlation has been found between the lack of fetal heart rate accelerations, the flatness of the record and poor neonatal outcome. In extreme situations (i.e. flatness in less than 10% of the record or in more than 80%) the presence or absence of accelerations does not add further useful information. Such information, however, is gained in the intermediary situations (the 'combined' recordings) and particularly when the record is between 51 and 80% flat where there appears to be an 85.6% risk to the fetus. Consequently, when trying to analyse an antenatal record it seems advisable to take primarily into account the percentage of flat recordings (providing the records are numerous enough and of sufficient length). Then, in records between 10 and 50% flat, the presence or the lack of spontaneous decelerations requires consideration whereas, when the record is between 51 and 80% flat, it is the presence or absence of fetal heart rate accelerations which is important.

Apgar Score↗

Methoxychlor accelerates embryo transport through the rat reproductive tract.

The estrogenic pesticide methoxychlor (MXC) is known to reduce implantation, and, in our previous work, this reduction has been attributed to a direct effect on uterine function. The present study was designed to investigate the effect of MXC on embryo transport rate, another phenomenon that is vulnerable to estrogenic effects. MXC was administered by gavage, at 0, 100, 200, and 500 mg/kg/day, to groups of rats on Days 1-3 of pregnancy (Day 0 = sperm positive), and the distribution of embryos in the oviducts and uteri of animals was assessed at five time intervals prior to implantation. No effect of MXC was detected by the afternoon of Day 1. On Days 2 and 3 of pregnancy, 200 and 500 mg/kg/day MXC were found to accelerate embryo transport into the uterus; the 500 mg/kg/day dosage also reduced the total number of embryos recovered from the tract. On the third day, 100 mg/kg/day MXC also accelerated embryo transport to the uterus and 200 mg/kg/day MXC reduced total embryo recovery. Until the afternoon of Day 3, most control embryos remained in the oviduct. These data demonstrate that MXC produces a dose-dependent acceleration of embryo transport through the female reproductive tract. When compared with previous work, the current data indicate that such an acceleration is the primary cause of MXC-induced preimplantation embryonic loss when exposure occurs after fertilization.

Animals↗

Effect of the BXSB Y chromosome accelerating gene on autoantibody production.

The Y chromosome of the BXSB mouse is able to accelerate and adversely alter the autoimmune disease of inbred BXSB mice and in male F1 hybrids. In order to further study the effects of the BXSB Y chromosome, we developed three inbred congenic strains, each bearing the BXSB Y: CBA/J.BXSB-Y, NZW.BXSB-Y, and NZB.BXSB-Y. The BXSB Y did not induce anti-DNA or anti-red blood cell (RBC) autoantibodies in either CBA/J or NZW congenic strains. Thus, it is an accelerating rather than an inducing factor. NZB.BXSB-Y congenic mice had accelerated anti-RBC but not anti-DNA. Studies of recombinant inbred by BXSB F1 mice indicated that the BXSB Y did not act to promote the activity of the NZB gene underlying anti-DNA. These and studies of (BXSB X NZB.BXSB-Y) F1 mice suggested that BXSB autosomal genes are required for the full anti-DNA accelerating activity of the BXSB Y. These mice provide a basis for future molecular genetic studies of the BXSB Y.

Animals↗

Pharmacological separation of cardio-accelerator and vagal inhibitory capacities of sympathetic nerves.

Prolonged attenuation of vagal action at the heart, proposed to be due to release of the sympathetic cotransmitter neuropeptide Y (NPY), follows stimulation of cardiac sympathetic nerves. It has been shown that pretreatment with reserpine depletes cardiac and neuronal stores of both noradrenaline and NPY, while combined pretreatment with reserpine and the ganglion blocking agent chlorisondamine reduces depletion of NPY, while still depleting noradrenaline. The effects of reserpine pretreatment and combined chlorisondamine and reserpine pretreatment on the inhibition of cardiac vagal action evoked by cardiac sympathetic nerve stimulation (16 Hz, 2 min) were compared in anaesthetised dogs. In dogs with no pretreatment (n = 6), sympathetic stimulation evoked an immediate cardio-acceleration, and a prolonged inhibition of cardiac vagal action, with a maximum percent inhibition (MPI) and time to half-recovery (T50) of 78 +/- 6% and 16 +/- 2 min respectively. In dogs pretreated with reserpine (n = 6, 1 mg/kg, 24 h), the immediate cardio-acceleration (ANOVA, P < 0.01), and the magnitude (MPI = 31.8%, ANOVA, P < 0.001) and duration (T50 = 6 +/- 1 min, ANOVA, P < 0.05) of inhibition of cardiac vagal action following sympathetic stimulation were significantly attenuated. In dogs with combined chlorisondamine (n = 5, 2 mg/kg, 48 and 24 h) and reserpine pretreatment, there was again significantly reduced cardio-acceleration (ANOVA, P < 0.01), but the inhibition of cardiac vagal action following sympathetic stimulation did not significantly differ from untreated animals (MPI = 79 +/- 8%, T50 = 21 +/- 6 min). Intravenous injections of NPY (25-50 micrograms/kg) evoked prolonged inhibition of cardiac vagal action in untreated and both groups of pretreated animals. These experiments indicate that the cardio-accelerator and vagal inhibitory capacities of sympathetic nerve stimulation can be separated, and are consistent with the sympathetic vagal inhibitory factor being NPY.

Animals↗

Age-related changes in levels of the beta-subunit of nerve growth factor in selected regions of the brain: comparison between senescence-accelerated (SAM-P8) and senescence-resistant (SAM-R1) mice.

Senescence-accelerated mice (SAM-P8) are characterized as mice in which aging is accelerated and memory disturbances occur. In several regions in the brain of SAM-P8 mice at 2, 4 and 8 months of age, we examined the concentrations of the beta-subunit of nerve growth factor (beta-NGF) and nine kinds of proteins such as S100 beta and alpha B-crystallin, and compared them with those in senescence-resistant mice (SAM-R1, as controls) at corresponding ages. Levels of beta-NGF in the hippocampus of SAM-R1 and SAM-P8 mice were reduced at 8 months of age. However, the decrease was more conspicuous in SAM-R1 than in SAM-P8, resulting in a significant difference between them (P < 0.01). The concentrations of beta-NGF in the cerebral cortex and cerebellum decreased to some extent with age in the control mice while it remained unchanged in the mutant mice. By contrast, the olfactory bulbs from SAM-R1 and SAM-P8 retained almost constant levels of beta-NGF during the first 8 months. However, its level was already higher in SAM-P8 at 2 months than in SAM-R1. Among nine proteins measured here, the acceleration of age-related increase was apparent in the levels of S100 beta and Mn-SOD in the cerebral cortex from SAM-P8. By contrast, the cerebral cortex and cerebellum from SAM-P8 showed tendencies to contain significantly high levels of alpha B-crystallin. These results suggest, at least, the presence of fibrous gliosis at quite an early age as well as the acceleration of senescence, in selected regions of the brain of SAM-P8.

Aging↗

Serum testosterone, 5-alpha-dihydrotestosterone and different sex characteristics in male fallow deer (Cervus dama): a long-term experiment with accelerated photoperiods.

To investigate the photoperiodic influence on androgen, testis volume, neck girth, and antler-cycles, five fallow bucks were exposed consecutively to different accelerated photoperiodic cycles (three 6-month, three 4-month, and one 3-month cycle). All parameters immediately followed artificial light cycles. Unlike in natural conditions, antler casting, regrowth, and velvet shedding occurred at decreasing day-lengths. The experiment provided further evidence that in fallow bucks the reproductive system is under strictly photoperiodic control and directly and/or indirectly dictates the course of the antler cycle via gonadal hormones. Depending on the test-system, the experiment revealed similar threshold values for the effect of testosterone (T) and/or 5-alpha-dihydrotestosterone (DHT) concentrations on the antler cycle as previously detected in fallow bucks living under natural conditions. Antlers were cast when T levels dropped below 3 ng/ml, and velvet shedding occurred after T and/or DHT values reached at least 5 to 7 ng/ml. In all cases, amplitudes of androgens remained lower than observed under natural conditions. Frequently during early antler growth, DHT values appeared higher than T levels. With increasing acceleration of the photoperiod, the antler cycle achieved limits of adaptation. The faster the photoperiods were accelerated, the smaller the antlers were developed. In addition, the antler tips were porous, blunt, and not completely mineralized. In all animals, accelerations of the photoperiods evoked phase displacements between measured parameters, pointing to an increasing internal desynchronisation. The present results indicate that the whole reproductive system of fallow deer is directly controlled by the photoperiod and that related morphological and physiological processes are indirectly determined by photoperiodic changes.

Animals↗

Cardiac, respiratory and metabolic changes during static exercise and voluntary heart rate acceleration.

Various ventilatory and metabolic parameters were monitored in 12 subjects while they performed each of three tasks: Voluntary cardiac acceleration with the aid of continuous heart rate feedback; a static hand-grip exercise at 1/3 maximum voluntary contraction; and a combined task involving both voluntary acceleration and exercise. Task order was counterbalanced across subjects and there were six 30 sec trials of each task. While reliable cardiac accelerations were recorded throughout, they were substantially greater with the combined task. This confirmed previous findings attesting that individuals can voluntarily elevate heart rate above levels induced by standard physical loads. However, the pattern of results for oxygen consumption and carbon dioxide production, with the most substantial increase in both also occurring for combined voluntary acceleration and exercise, suggested that the cardiac elevations superimposed on exercise levels were largely non-specific, i.e. they involved additional energy expenditure. Respiration volume increased during the performance of all three tasks, with the greatest increase again occurring in the combined tasks. The precise respiratory adjustments, in terms of rate and tidal volume, varied subtly among tasks; while all three tasks produced a rise in respiration rate, only the combined task increased tidal volume.

Adult↗

Inhibition of phorbol ester-accelerated amino acid transport in bovine lymphocytes.

12-O-Tetradecanoylphorbol-13-acetate, a highly active tumor-promoting agent and lymphocyte comitogen, rapidly accelerates the transport of alpha-aminoisobutyric acid in cultured bovine lymphocytes. Structure-activity studies show that the ability of phorbol diesters to accelerate alpha-aminoisobutyric acid uptake runs parallel to their potency as lymphocyte comitogens and as tumor promoters in mouse skin. This phorbol ester-accelerated, amino acid transport is largely insensitive to the inhibition of RNA and protein synthesis by actinomycin D and cycloheximide, respectively, and is insensitive to the inhibition of membrane movement by cytochalasin B and colchicine. Retinoic acid, an antagonist of the tumor-promoting and comitogenic actions of phorbol esters also inhibits the acceleration of amino acid uptake by 12-O-tetradecanoylphorbol-13-acetate; however, the epoxy derivatives of retinoic acid and structurally related analogs, which are potent antagonists of the other aspects of phorbol ester activation of lymphocytes, are inactive in blocking amino acid uptake. Comparative studies in lymphocytes show that this phorbol ester elicits a number of metabolic responses which appear to originate at the cell membrane and that these are differentially antagonized by retinoic acid, the 5,6-epoxide of retinoic acid, and related retinoid analogs.

Aminoisobutyric Acids↗

Accelerated fractionation vs hyperfractionation: rationales for several treatments per day.

Treatment with several doses per day offers the prospect of a significant therapeutic gain using readily available low LET beams. These regimens can be classified as either accelerated fractionation or hyperfractionation according to their rationales. With accelerated fractionation a conventional number of dose fractions is delivered in a significantly shortened overall treatment time in order to reduce the opportunity for tumor cell regeneration during treatment. With hyperfractionation, on the other hand, a large number of significantly reduced dose fractions is used to give a greater total dose in a conventional overall treatment time. The rationale for this strategy is threefold: 1) increased opportunity for tumor cell redistribution and reoxygenation between dose fractions: 2) a possibly lower oxygen enhancement ratio with small incremental doses; and 3) different sparing of late reacting normal tissues with small dose fractions. A review of the published clinical experience with multiple fractions per day treatment reveals few studies of either pure accelerated fractionation or hyperfractionation since both are limited by acute normal tissue reactions. This has led to a variety of hybrid regimens, some of which have no clear rationale. The choice between accelerated fractionation and hyperfractionation is determined by the regenerative capability of tumor clonogens during treatment. A method of selection based on potential doubling times is presented.

Clone Cells↗

The predictive value of cell kinetic measurements in a European trial of accelerated fractionation in advanced head and neck tumors: an interim report.

The value of cell kinetic measurements in head and neck tumors in predicting which patients will benefit from accelerated fractionation radiotherapy regimens is being tested in a multicenter European trial (EORTC trial 22851). This paper reports on the first analysis of the correlation of kinetics with outcome in this trial. A proportion of patients in both the accelerated arm (72 Gy in 5 weeks, 1.6Gy per fraction, 45 fractions) and the conventional arm (70-72 Gy in 7-8 weeks, 1.8-2.0 Gy per fraction, 35-40 fractions) were given an i.v. injection of 100 mg/m2 IUdR (iododeoxyuridine) before treatment, and a tumor biopsy was taken several hours later. The potential doubling time of the tumor (Tpot) was obtained from a flow cytometric analysis of tumor cell nuclei using an anti-IUdR antibody. From a total of 260 patients entered in the trial, 53 have undergone kinetic analysis. Adequate IUdR labeling was seen in 47 patients (88.7%), from which the mean value for Tpot was found to be 4.5 +/- 2.5 days (+/- S.D.). Of the IUdR labeled patients, 30 have now been followed up for at least 1 year, 17 with conventional and 13 with accelerated radiotherapy. These patients were split into those with fast and those with slowly growing tumors, the dividing line being the median Tpot value of 4.6 days. After conventional 7-week radiotherapy, 2 of 6 patients with "fast" growing tumors obtained local control compared with 8 of 11 with "slow" growing tumors. A small difference in local control was seen been fast and slow tumors in the accelerated arm (5/9 vs. 3/4). These preliminary data support the hypothesis that patients with fast growing tumors do poorly with conventional radiotherapy and that pretreatment kinetic measurements can select patients at risk. The predictive power of the method must await the final analysis of trial results.

Cell Division↗

Initial experience with a practical hyperfractionated accelerated radiotherapy regimen.

This paper presents early results of a trial of a three-fractions-per-day (TID) regimen that is more convenient to schedule than the Continuous Hyperfractionated Accelerated Radiotherapy (CHART) protocol currently being tested in Europe. The treatment schedule used in the CHART regimen has been modified from 36 fractions of 1.5 Gy TID in 12 days to 72 fractions of 1.1 Gy in 24 treatment days, with all fractions delivered during normal working hours. With no weekend treatments, the entire course of radiotherapy is completed in less than 5 weeks. The doses used were determined using the L-Q model, with correction for incomplete repair between fractions and for accelerated repopulation of cancer cells. Comparison with historical controls shows statistically significant improvements both in CR rates for the primary tumor and in acute toxicity, as measured by reduced treatment interruptions. L-Q model calculations predict that, compared to the highest dose achieved in previous studies without exceeding tolerance, we are able to obtain a 12% increase in bioeffect dose to the primary tumor due to accelerating the treatment. An analysis of the potential tumoricidal effectiveness of this new treatment regimen shows that it should be better than several other accelerated fractionation schedules being tested for all values of Tpot. For short Tpot times, the advantage may be as much as one log cell kill, corresponding to a 10-15% potential improvement in local control.

Aged↗

Accelerated superfractionated irradiation for advanced carcinoma of the head and neck: concomitant boost technique.

Between 1980 and 1988, 94 patients with AJCC Stage III and IV squamous cell carcinoma of all sites of the upper aero-digestive tract were treated with radiotherapy. We report here on 62 patients who are followed for a minimum of 2 years. Of these, 30 patients were treated with conventional once-a-day radiotherapy and 32 patients were irradiated using an accelerated superfractionation regimen during part of the treatment course. The altered fractionation schedule employed a concomitant boost technique with clinically demonstrable disease being irradiated twice-a-day during the first or second half of the treatment course. Daily radiation fractions were 1.8 Gy and the boost field was treated with 1.6 Gy after a 4- to 6-hr interval. No significant differences in acute treatment toxicity were observed in the two treatment groups. Patients treated with conventional and accelerated fractionation regimens experienced 36 months actuarial local tumor control rates of 40% and 67% (p = 0.03), respectively, which translated into an actuarial disease-free survival of 40% and 64% (p = 0.04). The increased locoregional control rates in patients treated with accelerated fractionation were associated with an adjusted and overall survival advantage at the p = 0.05 level. We conclude that our regimen of accelerated superfractionated irradiation with shortening of the treatment course resulted in improved control and survival rates at conventional doses of 68.4 to 73.8 Gy.

Adult↗

A prospective trial of accelerated radiotherapy in the postoperative treatment of high-risk squamous cell carcinoma of the head and neck.

PURPOSE: To evaluate the feasibility and toxicity of accelerated fractionation in the postoperative setting in high risk squamous cell carcinoma of the head and neck. METHODS AND MATERIALS: Thirty-two patients with high risk pathologic features (e.g., extracapsular extension, positive margins, > or = 4 nodes positive, perineural invasion) were enrolled in an accelerated fractionation schedule, using a modification of the M.D. Anderson concomitant boost technique delivering 63 Gy in 5.3 weeks at 1.8 Gy per fraction. RESULTS: Thirty patients (94%) completed treatment per protocol. Confluent mucositis was seen in 22 (69%) and five patients (22%) required 2 to 4 months for complete healing. Only five patients (16%) lost more than 10% of body weight. At a median follow-up of 32 months (range 22-42 months), the crude infield failure rate is 8/32 (25%). Infield recurrence was significantly associated with the interval from surgery to commencement of radiotherapy; 0/10 (0%) patients beginning radiotherapy within 4 weeks of surgery had infield failures compared to 8/22 (36%) for patients beginning radiotherapy more than 4 weeks after surgery (p = 0.035). CONCLUSION: While acute side effects appear to be increased compared to conventional radiotherapy, we conclude that postoperative accelerated radiotherapy is feasible and has acceptable toxicity in this population. These results support the concept of rapid tumor repopulation after resection. A randomized multi-institutional trial is currently underway to compare conventional and accelerated fractionation in the postoperative setting.

Adult↗

Adjuvant postoperative accelerated hyperfractionated radiotherapy in rectal cancer: a feasibility study.

PURPOSE: To assess the acute toxicity and hence feasibility of postoperative hyperfractionated accelerated radiotherapy in rectal cancer. METHODS AND MATERIALS: Twenty patients were submitted to accelerated hyperfractionated radiotherapy after resection of rectal cancer. A total dose of 48 Gy was given in 3 weeks. Two fractions of 1.6 Gy were used with a mean interfraction interval of at least 6 hours. The pelvic volume was treated by a four-field box technique using a linear accelerator (6-18 MV). Acute toxicity was assessed once per week. Small bowel and skin toxicity were scored according to the criteria of the World Health Organization. Bladder toxicity was scored according to the criteria of the Radiation Therapy Oncology Group. RESULTS: All the patients underwent the treatment as planned except one. No patient presented grade 3 or 4 bladder toxicity. There was only one patient who complained from grade 3 skin toxicity at the end of the treatment. Fourteen patients had some degree of intestinal toxicity. This was the most frequently occurring acute side-effect. Only two out of the fourteen patients had intestinal toxicity exceeding grade 2. CONCLUSION: Hyperfractionated accelerated radiotherapy on a pelvic volume is feasible as far as acute toxicity is concerned.

Adenocarcinoma↗

A phase III study of accelerated radiotherapy with and without carboplatin in nonsmall cell lung cancer: an interim toxicity analysis of the first 100 patients.

PURPOSE: In 1989 we initiated a multicenter randomized trial to determine if accelerated radiotherapy with or without concurrent carboplatin improves local control and survival in patients with limited nonsmall cell lung cancer. This interim analysis was performed on the first 100 patients to determine whether the toxicity of the four treatment arms is acceptable. METHODS AND MATERIALS: One hundred patients with limited nonsmall cell lung cancer have been randomized to receive one of four treatments: arm I, radiotherapy 60 Gray (Gy) in 30 fractions in 6 weeks; arm II, accelerated radiotherapy 60 Gy in 30 fractions in 3 weeks; arm III, radiotherapy as in arm I plus carboplatin 350 mg/m2 during weeks 1 and 5 of radiotherapy; arm IV, radiotherapy as in arm II plus carboplatin 350 mg/m2 during week 1. Survival was measured for the group as a whole and treatment-related toxicities in the four arms were compared. RESULTS: The estimated median survival for all 100 patients was 17.1 months with 33% estimated survival at 2 years. The major toxicities were hematologic and esophageal. Patients receiving carboplatin had more neutropenia (p < 0.0001) and thrombocytopenia (p = 0.002) than patients receiving radiotherapy alone, and this was most marked in patients on arm III. Both carboplatin and accelerated radiotherapy separately caused more severe esophagitis when compared to conventional radiotherapy alone (p = 0.011 and p = 0.0017, respectively). Esophagitis was more prolonged in patients having accelerated radiotherapy (p < 0.0001, median duration 3.2 months compared with 1.4 months for patients receiving conventional fractionation). Six patients (23%) treated on arm II have required dilatation of esophageal stricture, one dying with a laryngo-esophageal fistula. CONCLUSION: In patients receiving radiotherapy for unresectable lung cancer, overall treatment time can be halved and carboplatin administered concurrently with increased but acceptable esophageal and hematologic toxicity.

Adult↗

Accelerated hyperfractionated radiotherapy for malignant gliomas.

PURPOSE: To evaluate accelerated hyperfractionated radiotherapy for the treatment of malignant gliomas. METHODS AND MATERIALS: Between April 1985 and June 1994, 70 adult patients with pathologically confirmed malignant glioma (75% glioblastoma multiforme, 25% anaplastic astrocytoma) suitable for high-dose therapy were selected for treatment with accelerated hyperfractionated radiotherapy, 1.5 Gy twice daily to a total target dose of 60 Gy. Two patients were excluded from analysis (one patient had a fatal pulmonary embolism after 18 Gy; one patient discontinued therapy after 28.5 Gy against medical advice and without sequelae or progression). The 68 patients in the study group had a median age of 52 years and a median Karnofsky performance status of 90. Stereotactic implant (125I) or stereotactic radiosurgery boosts were delivered to 16 patients (24%) in the study group. Minimum follow-up was 6 months. RESULTS: Median survival was 13.8 months and median progression-free survival was 7.4 months. The absolute Kaplan-Meier survival rate was 16% at 2 years and 4% at 5 years. Multivariate analysis for the prognostic impact of age, gender, histology, Karnofsky performance status, symptomatology, surgical resection vs. biopsy, and boost vs. nonboost therapy revealed that Karnofsky performance status > or = 90, boost therapy, and surgical excision predicted significantly improved outcome. No severe toxicity occurred in patients treated with accelerated hyperfractionated radiotherapy alone, although 5% required steroids temporarily for edema. Progression occurred during treatment in one patient (1.5%). CONCLUSION: This regimen of accelerated hyperfractionated radiotherapy is well tolerated and leads to results comparable with those of standard therapy. The rate of disease progression during treatment is significantly better (p = 0.001) than is reported for patients treated with standard fractionation, with or without chemotherapy. This regimen is a reasonable starting point for future trials and may have some advantages over standard fractionation.

Adolescent↗

Cost effectiveness of accelerated rehabilitation after proximal femoral fracture.

A randomised controlled trial comparing an accelerated rehabilitation program after proximal femoral fracture with conventional care and rehabilitation was conducted with 252 elderly patients treated at an Australian general hospital in 1989/1990. This paper presents a cost-effectiveness analysis of the accelerated rehabilitation program. The measure of cost was all direct costs of treatment and subsequent care (medical and non-medical) incurred during the 4 months after fracture. Effectiveness was defined as whether the patient returned to semi-independent living; or if moderately or severely disabled prior to the fracture to the premorbid level of physical independence. The cost for treatment up to 4 months after fracture was estimated at A$ 10,600 per accelerated rehabilitation patient and A$ 12,800 per conventional care patient (1990 Australian dollars, A$). Thus, accelerated rehabilitation releases resources equivalent to approximately 17% of costs for treatment per patient. When cost effectiveness is considered, the potential cost savings rise to 38% per recovered patient.

Activities of Daily Living↗

Travel-related hepatitis B: risk factors and prevention using an accelerated vaccination schedule.

Rates of global travel and tourism are increasing dramatically, especially to regions with medium or high endemicity for hepatitis A and B, such as Asia, Africa, Latin America, and the Middle East. International travelers to these areas should be protected against both hepatitis A and B, regardless of their anticipated length of stay. However, many travelers depart within weeks of planning their trip (too late to complete the accelerated 0-, 1-, 2-month regimen for hepatitis B), and a majority of those traveling depart without being vaccinated. Although extended-stay travelers are at high risk for hepatitis B, short-stay travelers also are at risk. The most commonly encountered risk factors for travel-related hepatitis B are casual sexual activity with a new partner, medical and dental care abroad, and in the expatriate community, adoption of children who are hepatitis B carriers. Although efficacy studies of accelerated schedules for hepatitis B immunization have not been conducted, the results of immunogenicity studies in healthy volunteers who received an accelerated, 3-dose regimen on a 0-,7-, and 21-day schedule suggest that excellent, rapid, and long-term protection will be conferred. More data are needed to assess the efficacy of accelerated schedules in persons aged >40 years and to determine whether a fourth dose of hepatitis B vaccine is needed in all age groups.

Hepatitis B↗