Back injury in municipal workers: a case-control study.

Objectives: The purpose of this study was to identify factors associated with acute low back injury among municipal employees of a large city.

Methods: For each of 200 injured case patients, 2 coworker controls were randomly selected, the first matched on gender, job, and department and the second matched on gender and job classification. In-person interviews were conducted to collect data on demographics, work history, work characteristics, work injuries, back pain, psychosocial and work organization, health behaviors, and anthropometric and ergonomic factors related to the job.

Assisted hatching with or without bovine oviductal epithelial cell co-culture for poor prognosis in-vitro fertilization patients.

Older patients and those who consistently return for embryo transfer but without implantation were studied to see if a combination of day 3 assisted hatching and co-culture (AH+CC) might be beneficial compared to assisted hatching alone (AH-alone). Female patients of > or = 38 years and couples who had previously failed to implant embryos three times or more were prospectively and randomly assigned to either an experimental or a control group. In the experimental group all embryos were co-cultured on partial monolayers of bovine oviductal epithelial cells for 2 days followed by assisted hatching by zona drilling (AH+CC).

Treatment of male infertility and idiopathic failure to fertilize in vitro with under zona insemination and direct egg injection.

Objective: Failure to fertilize eggs in vitro may be countered by micromanipulation of gametes to place selected spermatozoa underneath the zona pellucida of the egg or directly into the egg, thereby improving chances of fertilization and production of viable embryos. Analysis of our clinical data for assisted fertilization was undertaken to assess those factors of relevance in this therapy, and a description of our procedures are given.

Study Design: Retrospective analysis of 85 cycles (73 couples) of in vitro fertilization and embryo transfer performed at a private infertility clinic, in which micromanipulation for assisted fertilization was used to overcome either severe male factor infertility or idiopathic failure to fertilize, was performed.

The effects of Vero (green monkey kidney) cell coculture on the motility patterns of cryopreserved human spermatozoa.

Objective: To determine the effects of Vero (a primate, urogenital epithelium-derived cell line) cell monolayer coculture on cryopreserved human sperm function in vitro.

Design: Prospective, controlled investigation in which cryopreserved semen specimens were thawed, processed, and then simultaneously exposed to control media (Dulbecco's modified Eagle's medium with either 10% heat-inactivated fetal bovine serum [FBS] or 10% heat-inactivated pooled human sera [PHS]) or the same media with the addition of confluent Vero cell monolayers. A second series of investigations was also performed to study the effect of Vero cell conditioned media (CM).

Chemical removal of the outside of the zona pellucida of day 3 human embryos has no impact on implantation rate.

Two hundred eighteen consenting patients entered a randomized study of the application of chemical zona pellucida thinning on their day 3 embryos, prior to uterine transfer. Of those control patients (n = 108), whose embryos remained unmanipulated, 40 (37.0%) have ongoing/delivered pregnancies, while in the experimental group (n = 110), whose embryos had their zonae pellucidae chemically thinned, there are 49 patients (44.

Repeated sperm injection under the zona following initial fertilization failure.

When fertilization fails following micromanipulative under-zona insemination, it is possible to repeat the procedure adding more spermatozoa to achieve fertilization, embryonic development and pregnancy. We report on 18 human in-vitro fertilization cycles where this approach was used. In nine cycles only late-fertilized embryos were available for transfer, and these gave rise to two viable pregnancies (22.

Electroejaculation in combination with in vitro fertilization and gamete micromanipulation for treatment of anejaculatory male infertility.

Objective: Failure to ejaculate may be overcome by use of electroejaculation. However, such semen samples are often unsuitable for therapies like intrauterine insemination. The combination of electroejaculation with in vitro fertilization, including gamete micromanipulation, should improve chances of fertilization and pregnancy in such cases.

Partial dissection of the zona pellucida of frozen-thawed human embryos may enhance blastocyst hatching, implantation, and pregnancy rates.

The rate of successful implantation after replacement of frozen-thawed embryos in in vitro fertilization is commonly only 5% to 10% per embryo. A limiting factor may be inability of otherwise viable embryos to be released from the intact zonae pellucidae. Culture conditions and/or cryopreservation in in vitro fertilization may affect the zona and impair blastocyst hatching.

Routine application of partial zona dissection for male factor infertility.

Partial zona dissection (PZD) increases the chances of fertilization by improving the access of spermatozoa to the perivitelline space (PVS) helping those spermatozoa unable to penetrate the zona pellucida (ZP) and possibly those poorly able to penetrate the oolemma. Problems arise in assessing semen to decide which parameters might indicate defects of this nature. PZD, by circumventing the ZP, may also increase the rate of polyspermy, especially in infertility where ZP and oolemmal penetration are not defective.

Recognition of paternal pronuclei in human zygotes.

The possibility of pronuclear gender determination using morphological criteria only was investigated in 140 two-pronucleate and 39 tripronucleate zygotes. Zygotes were videotaped on different focal points and the positions of the polar bodies, pronuclear diameters, number and distribution of nucleoli, and presence of sperm tail remnants were indicated on diagrams. The three known criteria used for recognition of the paternal pronucleus in rodent zygotes were investigated.

Observations on the morphology of pronuclei and nucleoli in human zygotes and implications for cryopreservation.

The effects of cryopreservation on human zygotes at various stages between the appearance of pronuclei and their close association were investigated. Pronuclear zygotes (n = 233) from 101 patients were frozen using propanediol 21-35 h following egg collection. The incidence of implantation of thawed pronuclear zygotes frozen 29-35 h following oocyte collection was significantly higher than that of younger pronuclear zygotes (28 versus 10%, respectively).

Coculture of human zygotes on fetal bovine uterine fibroblasts: embryonic morphology and implantation.

Zygotes from in vitro fertilization patients (n = 116) were randomly allocated to culture in either conventional plastic petri dishes or coculture on a monolayer of fetal bovine uterine fibroblasts. Embryos (n = 288) remained 26 to 32 hours in these culture systems. Video tape recording for later morphological analysis (11 parameters) was performed on 117 conventionally cultured and 104 cocultured embryos, shortly before replacement, by an independent observer, unaware of the culture conditions for each embryo.

Arm posture and human movement capability.

Many workers perform manual assembly tasks or use hand tools while the hands are postured above the shoulders or to the side of the body. Experiments were conducted to study the sensitivity of speed-accuracy movement performance to a wide range of hand locations around the shoulder under various levels of hand loads, ratios of work to rest, and task durations. Subjects performed a spatially constrained stylus-to-hole Fitts reciprocal movement task designed to simulate high-incentive manual assembly operations while providing basic information regarding changes in human move and positioning capabilities.

In-vitro development and implantation of human embryos following culture on fetal bovine uterine fibroblast cells.

Human zygotes resulting from IVF were placed in two different culture systems to evaluate in-vitro development and to establish pregnancies in patients following embryo replacement. Treatment A (control) consisted of culturing zygotes in a modified Earle's Balanced Salt solution while treatment B consisted of culturing zygotes on a monolayer of fetal bovine uterine fibroblasts in this same culture medium. At the time of embryo replacement, embryos within treatments A and B had 3.

Videocinematography of fresh and cryopreserved embryos: a retrospective analysis of embryonic morphology and implantation.

Eleven morphologic criteria were studied from videotapes of 323 fresh and 103 thawed embryos. The proportion of thawed embryos (30/39; 77%) with more than one abnormality was (P = 0.03) higher than that of fresh embryos (5/13; 38%), despite similar implantation rates (18% and 15%, respectively).

Shoulder posture and localized muscle fatigue and discomfort.

In many industries workers perform manual assembly tasks with hands postured above the shoulders. Awkward shoulder and arm postures are often viewed as acceptable given costs of workplace modification, postural exertions which are in compliance with current design recommendations, ready availability of strong workers, and numbers of electromyographic studies which fail to detect significant signs of localized muscle fatigue (LMF). An experiment was conducted to: (a) study the onset and severity of (LMF) in the shoulder when performing a stylus-to-hole Fitts reciprocal movement task under a range of postures, hand loads, ratios of work-to-rest, and task durations, and (b) to evaluate the efficacy of three techniques (i.

Duration of storage of cryopreserved human embryos.

The incidence of cell injury, embryo survival, and implantation following cryopreservation of zygotes and two- to five-cell embryos was studied in 100 patients in order to evaluate the effect of duration of storage. The incidence of individual cell survival was 58% regardless of the length of time kept in liquid nitrogen or the stage of the embryo at freezing. There were 104 of 208 (50%) thawed embryos that survived completely intact, and of those, 24 implanted successfully.

Performance evaluation tests for environmental research (PETER): code substitution test.

The effects of repeated testing on code substitution performance were studied in three experiments to determine reliability and stability of task performance under laboratory and at-sea conditions. In Exp. 1, a single 2-min.

Development of performance evaluation tests for environmental research (PETER): navigation plotting.

A navigation plotting task, modeled after actual shipboard navigation and plotting practices, was evaluated for inclusion in the Performance Evaluation Tests for Environmental Research (PETER) task battery. The differential stability of the 9-min self-paced task was examined independently in the laboratory and during a field study conducted at sea aboard three seagoing vessels. Repeated testing in both laboratory and field conditions showed that the percent correct metric was not reliable.

Susceptibility to seasickness: influence of hull design and steaming direction.

Three sea going vessels steamed side by side through slight seas off the coast of Oahu, Hi. A 4-h octagon was transmitted twice each day for three consecutive days while motion sickness symptomatology was recorded from 18 enlisted men who alternated among the vessels. Dramatic differences in illness severity were obtained whether comparisons were made using objective evidence of vomiting episodes or subjective reporting of symptoms on questionnaires.