Genetic variation for an aphid wing polyphenism is genetically linked to a naturally occurring wing polymorphism.

Many polyphenisms are examples of adaptive phenotypic plasticity where a single genotype produces distinct phenotypes in response to environmental cues. Such alternative phenotypes occur as winged and wingless parthenogenetic females in the pea aphid (Acyrthosiphon pisum). However, the proportion of winged females produced in response to a given environmental cue varies between clonal genotypes. Winged and wingless phenotypes also occur in males of the sexual generation. In contrast to parthenogenetic females, wing production in males is environmentally insensitive and controlled by the sex-linked, biallelic locus, aphicarus (api). Hence, environmental or genetic cues induce development of winged and wingless phenotypes at different stages of the pea aphid life cycle. We have tested whether allelic variation at the api locus explains genetic variation in the propensity to produce winged females. We assayed clones from an F2 cross that were heterozygous or homozygous for alternative api alleles for their propensity to produce winged offspring. We found that clones with different api genotypes differed in their propensity to produce winged offspring. The results indicate genetic linkage of factors controlling the female wing polyphenism and male wing polymorphism. This finding is consistent with the hypothesis that genotype by environment interaction at the api locus explains genetic variation in the environmentally cued wing polyphenism.

Dermal burn during hip arthroscopy.

Radiofrequency devices are often used during arthroscopic surgery, most commonly of the shoulder and knee, and increasingly in hip arthroscopy. The most commonly described complication is elevation of joint temperature, leading to capsular shrinkage, chondrolysis, and nerve damage. A less commonly reported complication is that of dermal burns from the heated irrigation fluid. There are several case reports describing dermal burns after shoulder arthroscopy; however, to the authors' knowledge, there are none describing the complication in hip arthroscopy that is often performed by surgeons doing limited if any shoulder arthroscopy. The authors report this case to raise awareness that the use of radiofrequency devices can also lead to extra-articular complications because of the effect of elevated irrigant fluid temperatures on the patient's skin. Sufficiently high temperatures were generated inside the joint, causing a superficial second-degree burn from the outflow irrigant. In the course of instrument switching from sucker/shaver to radiofrequency wand, the outflow valve was inadvertently left open with no attached suction while the radiofrequency wand was in use. Most second-degree burns like the one reported require only conservative therapy with cool compresses to decrease the temperature of the wound. The authors did recommend bacitracin ointment to prevent superficial wound infection, however unlikely with no disruption of the skin. The authors continue to use radio-frequency devices in hip arthroscopy, but are vigilant to maintain dedicated suction at the outflow tubing throughout the procedure. Surgeons should take strict precautions to avoid this preventable complication and follow all manufacturer instructions on the use of such devices.

Evaluation of appropriateness of patient transfers for hand and microsurgery to a level I trauma center.

BACKGROUND: The transfer of patients for hand and microsurgical emergencies to level I trauma centers is a common practice. Many of these transfers do not actually require a hand specialist and could be taken care of at most regional hospitals. In this study, we will evaluate the appropriateness of patient transfers for hand trauma and determine if there is a correlation between inappropriate transfers and undesirable factors, such as insurance status and off-hour's presentation. METHODS: A retrospective chart review was performed in all patients transferred to a level I trauma center for hand and microsurgical trauma over a 22-month period. Collected data included indication for transfer, mode of transfer, time and day of the week, patient demographics, insurance status, and whether the transferring facilities had surgical coverage available. A synopsis, including treatment details, of each transfer was created, and a survey was sent to a review committee who rated the appropriateness of the transfers. Statistical analysis was performed to determine whether appropriateness of transfers was influenced by nonmedical variables. RESULTS: Over a 22-month period, a total of 95 hand or microsurgical patients were transferred to a single tertiary referral center. Of these, 66 % of the transfers were considered inappropriate by the surveyed physicians. Inappropriate transfers were statistically more likely to be under insured or transferred during nonbusiness hours. CONCLUSION: A large percentage of patients are being transferred to tertiary care centers for reasons other than medical necessity, generating a large burden on already strained medical resources.

Effects of nandrolone on recovery after neurotization of chronically denervated muscle in a rat model.

OBJECT: Suboptimal recovery following repair of major peripheral nerves has been partially attributed to denervation atrophy. Administration of anabolic steroids in conjunction with neurotization may improve functional recovery of chronically denervated muscle. The purpose of this study was to evaluate the effect of the administration of nandrolone on muscle recovery following prolonged denervation in a rat model. METHODS: Eight groups of female Sprague-Dawley rats (15 rats per group, 120 in all) were divided into 3- or 6-month denervated hind limb and sham surgery groups and, then, nandrolone treatment groups and sham treatment groups. Evaluation of treatment effects included nerve conduction, force of contraction, comparative morphology, histology (of muscle fibers), protein electrophoresis (for muscle fiber grouping), and immunohistochemical evaluation. RESULTS: Although a positive trend was noted, neither reinnervated nor normal muscle showed a statistically significant increase in peak muscle force following nandrolone treatment. Indirect measures, including muscle mass (weight and diameter), muscle cell size, muscle fiber type, and satellite cell counts, all failed to support significant anabolic effect. CONCLUSIONS: There does not seem to be a functional benefit from nandrolone treatment following reinnervation of either mild or moderately atrophic muscle (related to prolonged denervation) in a rodent model.

Neurotrophic effects of perfluorocarbon emulsion gel: a pilot study.

BACKGROUND: Positive neurotrophic effects of hyperbaric oxygen treatment may be more easily achieved by applying a Perflourocarbon (PFC) emulsion gel to the repair site. PFCs are halogen substituted carbon oils with unique oxygen transport potentials that are capable of increasing oxygen availability in local tissues. The purpose of this study was to determine if the application of a PFC emulsion to a repaired nerve would improve recovery. MATERIALS AND METHODS: The left tibial nerve of 21 immature female Sprague-Dawley rats was transected, immediately repaired, and then circumferentially coated with PFC gel (Group A, n = 7), PFC-less gel (Group B, n = 7), or nothing (suture only, Group C, n = 7). At eight weeks post surgery, electrophysiological testing and histological and morphological analysis was performed. RESULTS: No statistically significant differences between experimental groups were found for muscle size and weight, axon counts, or nerve conduction velocity. Group A had a significantly smaller G-ratio than Groups B and C (p < .0001). CONCLUSION: Overall results do not indicate a functional benefit associated with application of a PFC emulsion gel to rodent tibial nerve repairs. A positive effect on myelination was seen.