[Research on the relationship between environmental chemical pollutant exposure and epigenetics].

Environmental chemical pollutants are increasing, which brings various harms to human health. Epigenetics may be an important medium between exposure to environmental chemical contaminants and adverse health effects. Many environmental chemical pollutant exposures can regulate gene expression and promote disease occurrence and development through epigenetic mechanisms. This review outlines the mechanisms of epigenetics and the latest research advances in exposure and epigenetics of several environmental chemical substances (heavy metal arsenic, bisphenol A, dioctyl phthalate and benzene). To further understand and study the relationship between environmental chemical pollutant exposures and epigenetics in order to elucidate the mechanisms of disease occurrence and development.

Parasitism of Spodoptera litura (Lepidoptera: Noctuidae) by Microplitis prodeniae (Hymenoptera: Braconidae).

Spodoptera litura Fabricius is a major vegetable pest that is widely distributed throughout tropical, subtropical and temperate regions. Microplitis prodeniae Rao and Chandry is a solitary endoparasitoid of S. litura. To assess the potential use of this parasitoid as a biological control agent, the reproductive schedule, fecundity and functional response of M. prodeniae were investigated under conditions of 28 ± 1°C and 70 ± 10% relative humidity with a 14:10-h L:D photoperiod. The parasitoid's average lifetime fecundity was 171.0 ± 10.4 eggs, of which approximately 50% were laid within the first 3 days. Additionally, M. prodeniae exhibited a Holling type II functional response, and the estimated maximum numbers of the 1st, 2nd and 3rd instar larvae that were parasitized by a single M. prodeniae female were 71.6, 78.4 and 41.5 larvae over a 24-h period, respectively. The results of this study suggest that M. prodeniae has great potential as a candidate for controlling S. litura and can guide efforts in its mass production.

Effects of cold storage on the biological characteristics of Microplitis prodeniae (Hymenoptera: Braconidae).

The endoparasitoid Microplitis prodeniae Rao and Chandry is an important potential augmentative biological control agent for lepidopteran pests of vegetables and tobacco. However, cold storage of pupae is required to ensure that sufficient parasitoids are available when they are needed in the field. In this study, pupae were maintained at 0, 4 or 10°C for 5-50 days after which the adults were evaluated for emergence, pre-emergence period, sex ratio, female longevity, oviposition period, and fecundity. Cold storage did not affect the pre-emergence period or proportion of females; however, there was a significant reduction in emergence, female longevity, oviposition period, and fecundity with increased exposure to cold. The pre-emergence period was approximately 5 days, and approximately 50% of the emergent parasitoids were females. A cold storage regime of 10 days at 10°C had no effect on the parasitoids and adult emergence was greater than 50% even after 20 days at 10°C. There was no carryover of the cold treatment from parental to F1 and F2 generations. Thus, M. prodeniae can be stockpiled for field release by exposing the pupae to a cold regime and subsequently holding them for adult emergence at 28°C.

Blood flow changes to the femoral head after acetabular fracture or dislocation in the acute injury and perioperative periods.

OBJECTIVES: Acute blood flow to the femoral head has been postulated to be affected negatively by traumatic acetabular fracture or dislocation. To the best of our knowledge, a prospective study that has examined acute changes in blood flow to the femoral head with respect to the timing of reduction and the effect of open reduction and internal fixation after acetabular fracture or dislocations has not been performed. DESIGN AND SETTING: From June 1994 to February 1996, fifty-four consecutive patients with hip dislocations with or without fractures of the acetabulum were entered into this investigation. The patients were categorized into three groups: isolated dislocations, fractures or dislocations requiring open reduction and internal fixation, and isolated acetabular fractures without dislocation but requiring open reduction and internal fixation. Single-photon emission computed tomography (SPECT) scans were obtained after relocations and preoperatively and postoperatively after open reduction and internal fixation of displaced acetabular fractures. RESULTS: The median dislocation time for all patients flow was 4.00 hours (range 1 to 24 hours). SPECT scanning showed a low blood flow pattern in five (9.25 percent) patients. A low blood flow pattern was seen in patients with early and late relocation times. Open reduction and internal fixation was not statistically associated with an avascular pattern of blood flow. Forty-two (78 percent) of our patients were available for follow-up, with an average of 24.3 months and a minimum of one year. There was one false-positive, one false-negative, and thirty-eight true-negative scans. CONCLUSIONS: A global loss of scintillation in the femoral head as determined by SPECT scanning occurs in some patients with hip dislocations and fractures or dislocations of the acetabulum in the early injury period. Changes in blood flow occurred in patients with short (one hour) and long (twenty-four hours) dislocation times. However, the development of avascular necrosis could not be predicted by early SPECT scanning. Until further multicenter studies are performed, SPECT scanning cannot be recommended on an acute or routine basis to predict those patients who will develop avascular necrosis. Operative approaches for open reduction of the hip and internal fixation of acetabular fractures do not appear to affect blood flow to the femoral head. Although a golden time to relocation cannot be fully established from this study, early relocation is advised to decrease the potential risk of vascular spasm, scarring, and subsequent avascular necrosis.

The floating knee in the pediatric patient. Nonoperative versus operative stabilization.

The results of nonoperative and operative or rigid stabilization of ipsilateral femur and tibia fractures in children and adolescents were evaluated. Twenty-nine consecutive patients with open physes (30 affected extremities) were reviewed. Their mean followup was 8.6 years (range, 1.1-18.6 years). The nonoperative group consisted of 16 patients and 16 extremities treated by skeletal traction of the femoral fracture, closed reduction and splinting or casting of the tibia fractures, and eventual immobilization in a hip spica cast. The operative group, was comprised of 13 patients and 14 extremities in which one or both fractures were treated by open reduction and internal fixation, intramedullary fixation, or external fixation. Despite higher modified injury severity scores and skeletal injury scores, the patients who were treated operatively had a significantly reduced hospital stay, 20.1 days versus 34.9 days, respectively; decreased time to unsupported weightbearing, 16.8 weeks compared with 22.3 weeks, respectively; and fewer complications. Operative stabilization of the femur had a significant effect on decreasing the length of hospital stay and the time to unassisted weightbearing. The patients also were analyzed according to their age at the time of injury: 9 years of age or younger and 10 years of age and older. The younger children who were treated nonoperatively had an increased rate of lower extremity length discrepancy, angular malunion, and need for a secondary surgical procedure as compared with younger children who were treated operatively with rigid fixation. Based on the results of the current study, operative stabilization of at least the femur fracture and, preferably, both fractures in the treatment of a child with a floating knee is recommended, even for younger children.

The role of internal fixation in the treatment of Jones fractures in diabetics.

The purpose of this study was to evaluate the treatment of fractures of the proximal fifth metatarsal at the junction of the metaphysis and diaphysis (i.e., Jones fracture) in diabetics. Open reduction and internal fixation with bone grafting resulted in clinical and radiographic union 8 weeks after surgery in patients treated with either immediate or delayed open reduction and internal fixation. Open reduction and internal fixation with autologous bone grafting is an effective treatment regimen in the diabetic patient with a Jones fracture. An initial trial of casting can be attempted without any apparent deleterious effects on secondary open reduction and internal fixation.

Posterior hip dislocations: a cadaveric angiographic study.

Avascular necrosis (AVN) of the femoral head after a traumatic posterior hip dislocation (Thompson and Epstein type I) has been hypothesized to occur due to changes in blood flow. However, to the best of our knowledge of the English literature, a human cadaveric angiographic study has never been performed to delineate these vascular changes. Six fresh frozen human cadavers were used to examine the effects of posterior hip dislocation on the extraosseous and intraosseous blood supply to the femoral head and neck. After a forceful posterior hip dislocation was performed on the cadavers, the proximal vessels were injected with a radioopaque colored latex liquid polymer (Microfil) and examined under cinefluoroscopy. The contra lateral hips were used as controls and were examined in a similar manner. Both hips of the cadavers were harvested, and a macroscopic and microscopic examination was performed. The cine-fluoroscopic examination delineated the dynamic effects of posterior dislocation on the surrounding vasculature. Filling defects were most notable at the junction of the external iliac and common femoral arteries. Filling defects were also present in the circumflex vessels. Compared to controls, the common femoral and circumflex vessel filling defects were statistically significant (p < 0.004). These defects were secondary to an apparent stretching and twisting of the artery caused by the pull and rotation of the dislocated hip. A number of collateral vessels from the gluteal arteries were also demonstrated on fluoroscopic examination. The macro and microscopic examination did not show a qualitative or a quantitative difference in the amount of latex present in the dislocated and control groups. Based on the results of this study, changes in the extraosseous blood flow to the dislocated hip do occur. The vessels that appear to be most affected by the dislocation are the common femoral and circumflex vessels. However, these extraosseous changes do not consistently result in changes in the intraosseous blood flow possibly due to collateral circulation. Relocating the femoral head in a traumatic posterior hip dislocation may provide earlier blood flow to the femoral head by relieving tension across the femoral and circumflex vessels. Delayed relocation could contribute to the development of AVN in the femoral head by not only inducing immediate ischemia at the time of injury but by also producing a progressive and delayed form of arterial damage in the femoral and circumflex vessels. AVN may not be an absolute outcome of posterior hip dislocations due to preexisting collateral circulation and/or the preservation of the femoral circumflex vessels.

Schwannoma of the superficial peroneal nerve presenting as web space pain.

A 55-year-old male presented complaining of pain at his right fourth toe and dorsal fourth web space. Physical examination findings pointed to a lesion affecting the superficial peroneal nerve. A schwannoma of the superficial peroneal nerve was subsequently excised, relieving the patient's symptoms. In the differential diagnosis of nontraumatic and/or nonarthritic toe and foot pain, benign tumors, including schwannomas of the tibial and peroneal nerves, should be considered.