Defensive chemistry of an aposematic bug, Pachycoris stallii Uhler and volatile compounds of its host plant Croton californicus Muell.-Arg

Volatile components of Pachycoris stallii scent gland secretions and the bug's host plant, Croton californicus, were identified by gas chromatography and mass spectroscopy. The predominant compounds isolated from C. californicus fruit and leaves were beta-myrcene and beta-caryophyllene. Metathoracic gland secretions of P. stallii contained mostly (E)-2-hexenal, (E)-4-oxo-2-hexenal, (E)-2-hexenyl acetate, and n-tridecane. In males, n-tridecane was present throughout the metathoracic gland, but in females this compound was found only in the median reservoir/accessory gland. (E)-2-Hexenal was present throughout the gland of female bugs, but in males was primarily present in the median reservoir/accessory gland. (E)-4-Oxo-2-hexenal and n-dodecane were isolated from the median reservoir/accessory gland of male and female bugs. Metathoracic glands were sexually monomorphic. Data from chemical analyses and anatomical observations suggest that dorsal abdominal glands of adults were apparently obsolescent. In nymphs, dorsal abdominal glands produced (E)-2-hexenal, (E )-4-oxo-2-hexenal, n-dodecane, n-tridecane, and tetradecanal. The proportion of the predominant constituent, (E)-4-oxo-2-hexenal, decreased from 72% in the first instar to 47% in the fourth instar. Proportions of tetradecanal and n-tridecane were greater in the fourth instar than in the first instar. Observations of dissected glands indicated that median and posterior dorsal abdominal glands of all nymphal instars were more developed than anterior dorsal abdominal glands. Scanning electron micrography revealed the presence of polygonal microsculpturing on the integument surrounding the ostioles of metathoracic and dorsal abdominal glands. Chemical, anatomical, and behavioral data indicated that P. stallii has a chemical defense system based on short-chain carbonyl compounds and that this system is directed against arthropods. The abundance of arthropod natural enemies apparently has forced P. stallii to maintain this defense system despite feeding on a toxic host plant.

Identification and characterization of a protein destruction signal in the encephalomyocarditis virus 3C protease

The amino acid sequence LLVRGRTLVV, which is probably located in a strand-turn-strand structure, has been identified as a protein destruction signal in the rapidly degraded encephalomyocarditis virus 3C protease. Mutations within this sequence reduced the susceptibility of the 3C protease toward ubiquitination and degradation in rabbit reticulocyte lysate. This signal is transferable, since poliovirus 3C protease, which is a poor ubiquitin-mediated proteolytic system substrate, was found to be ubiquitinated and degraded when the signal sequence was either generated at an internal location in the protein or fused to the N terminus. An evaluation of the behavior of 3C protease proteins containing mutations in the signal region indicates that considerable variability in the primary structure is tolerated, although the conservation of certain features appears to be required for signal function. Two E3 ubiquitin-protein ligases that recognize the encephalomyocarditis virus 3C protease as a substrate were also partially purified. One of these was identified as the previously described E3alpha, and this was shown to require the destruction signal sequence to catalyze efficiently the ubiquitination of the 3C protease. The other is a Ubc5-dependent E3 that appears to recognize a different, unidentified feature of the 3C protease.

Changes in tissue oxyhaemoglobin concentration measured using multichannel near infrared spectroscopy during internal carotid angiography

OBJECTIVE

To develop an in vivo model for testing spatially resolved spectroscopy and quantified near infrared spectroscopy (NIRS) cerebral blood flow measurements.

METHOD

Multiple detector NIRS has been used to study changes in tissue oxyhaemoglobin (O2Hb) concentration during selective internal carotid angiography. A significant reduction in O2Hb occurred in tissue interrogated by detectors situated between 0.7 and 4.1 cm from the NIRS light source.

RESULTS

The time course of O2Hb concentration change was consistent with displacement of oxygenated blood by the radiocontrast medium from vascular beds of differing flow and NIR light attenuation. Increasing changes in O2Hb concentration per unit photon path length--predicted to occur at greater emitter-detector separations if those changes had occurred predominantly in cerebral tissue--were found in the first four seconds after injection of radiocontrast medium. However, later changes (6-10 s) were larger and were not proportional to emitter-detector separation.

CONCLUSION

The findings indicate that simple assumptions regarding the distribution of the internal carotid artery blood supply to cerebral and extracerebral tissues, the photon path length through those tissues, and their relative contributions to attenuation of NIR light may not be justified.

African-American adolescents residing in high-risk urban environments do use condoms: correlates and predictors of condom use among adolescents in public housing developments

OBJECTIVE

African-American adolescents living in high-risk inner-city environments have been disproportionately affected by the epidemics of human immunodeficiency virus (HIV) and other sexually transmitted diseases. Understanding the factors that influence the use of condoms by adolescents is critical for developing effective behavioral interventions. The present study examined the demographic, psychosocial, and behavioral correlates of condom use among African-American adolescents residing in public housing developments in an HIV epicenter (San Francisco) and prospectively evaluated the stability of these significant cross-sectional variables to predict consistent condom use.

DESIGN

A prospective study.

SETTING

Two public housing developments in San Francisco.

PARTICIPANTS

African-American adolescents and young adults between 12 and 21 years of age were recruited though street outreach and completed a theoretically derived research interview assessing HIV-related knowledge, attitudes, and behaviors. After a 6-month period, adolescents completed a follow-up interview similar to the baseline measure. Among adolescents reporting sexual activity in the 6 months before completing the baseline interview (n = 116), logistic regression analysis evaluated the influence of demographic, psychosocial, and behavioral factors on consistent condom use.

RESULTS

Adolescents who had high assertive self-efficacy to demand condom use (adjusted odds ratio [OR], 11), perceived peer norms as supporting condom use (OR, 4.2), had greater impulse control (OR, 3.7), were male (OR, 4.7), and were younger (OR, 2.9) were more likely to report consistent condom use. Frequency of sexual intercourse was inversely related to condom use; adolescents with higher numbers of sexual episodes were less likely to use condoms consistently. Prospective analyses identified the baseline level of condom use as the best predictor of condom use at the 6-month follow-up. Adolescents who were consistent condom users at baseline were 7.4 times as likely to be consistent condom users during the follow-up period. Of those adolescents changing their frequency of condom use during the follow-up interval, significantly more engaged in risky behavior; 33.3% changed from consistent to inconsistent condom use, whereas 20.6% changed from inconsistent to consistent use (OR, 1.6).

CONCLUSIONS

The findings suggest that HIV prevention programs need to be implemented early, before high-risk behaviors are established and may be more difficult to modify.

Urban rape survivors: characteristics and prevalence of human immunodeficiency virus and other sexually transmitted infections. Multicenter Crack Cocaine and HIV Infection Study Team

OBJECTIVE

To determine the prevalence of recent rape, the characteristics or recent rape survivors, and the seroprevalence of human immunodeficiency virus (HIV), syphilis, and genital herpes (HSV-2) among recent rape survivors.

METHODS

We surveyed women 18-29 years old who were recruited from places unassociated with medical or drug treatment or the criminal justice system in three urban communities where illicit drug use is common. We compared characteristics and HIV, syphilis, and HSV-2 seroprevalence of women who reported recent rape with those of women who denied recent rape.

RESULTS

One hundred fifty-one of 1104 (13.7%) women reported having been raped in the year before our interview. Rape survivors were more likely than women who denied recent rape to smoke crack cocaine (86.8 versus 56.7%; odds ratio [OR] 5.0, 95% confidence interval [CI] 3.2-7.8), to be homeless (17.2 versus 6.1%; OR 3.2, CI 2.0-5.2), to report a recent sexually transmitted disease (38.7 versus 18.7%; OR 2.7, CI 1.9-3.9), and to be infected with syphilis (42.4 versus 28.4%; OR 1.9, CI 1.3-2.6) and HSV-2 (71.9 versus 57.5%; OR 1.9, CI 1.3-2.8). Survivors were more likely to acknowledge any HIV risk behavior (including sex work) (85.4 versus 49.5%; OR 5.9, CI 3.9-9.0) and to be HIV-infected (23.3 versus 13.4%; OR 1.9, CI 1.3-2.9). Rape was not independently associated with HIV (OR 0.8, 95% CI 0.4-1.3), syphilis (OR 0.9, 95% CI 0.6-1.3), or HSV-2 (OR 1.3, 95% CI 0.9-2.0) infections after adjustment for confounding factors.

CONCLUSION

One in seven women reported being raped recently. Rape was most common among sex workers, crack smokers, and the homeless. Most survivors reported HIV risk behaviors, and many were HIV-infected. Programs to prevent repeated rape, voluntary HIV counseling and testing, and other medical and social services may benefit survivors in these and similar communities.

A multicenter study on the use of pulsed low-intensity direct current for healing chronic stage II and stage III decubitus ulcers

BACKGROUND AND DESIGN

Pulsed low-intensity direct current (300 to 600 microA) has been used in a double-blind placebo multicenter study in the treatment of stage II and stage III chronic decubitus ulcers.

RESULTS

Seventy-four ulcers were treated in four centers. Forty-three patients were selected for the experimental group, and 31 control subjects used the sham instrument (placebo group). In the treated group, 25 ulcers (58%) healed in 8 weeks, whereas in the placebo group, only one ulcer (3%) healed and most ulcers increased in size. Statistical analysis, based on surface area and ulcer depth before and after treatment, showed that low-intensity direct current had a significant influence on the healing rates for these ulcers (P < .0001). Experiments with guinea pigs (n = 10) showed that pulsed low-intensity direct current caused a rapid calcium flux in the epidermis.

CONCLUSIONS

Pulsed low-intensity direct current represents a useful approach for the treatment of stage II and stage III chronic decubitus ulcers by increasing the healing rate. The growth of fibroblasts and keratinocytes may be enhanced by pulsed low-intensity direct current due to changes in calcium homeostasis.

Hydrostatic weighing without head submersion in morbidly obese females

This study tests the validity of hydrostatic weighing without head submersion (HWNS) for determining the body density (Db) of morbidly obese (MO) females. Eighty MO females who were able to perform traditional hydrostatic weighing at residual volume (HW) underwent four counterbalanced trials for each procedure (HW and HWNS) to determine Db. Residual volume was determined by oxygen dilution. Twenty subjects were randomly excluded from the experimental group (EG) and assigned to a cross-validation group (CV). Simple linear regression was performed on EG data (n = 60, means = 36.8 y, means % fat = 50.1) to predict Db from HWNS (Db = 0.569563 [Db HWNS] + 0.408621, SEE = 0.0066). Comparison of the predicted and actual Db for CV group yielded r = 0.69, SEE = 0.0066, E statistic = 0.0067, mean difference = 0.0013 kg/L. The SEE and E statistic for body fat were 3.31 and 3.39, respectively. Mean difference for percent fat was 0.66%. Results indicate that HWNS is a valid technique for assessing body composition in MO females.

Giant cell tumor in a patient with osteopoikilosis

A giant cell tumor developed in the distal femur of a 26-year-old man with preexisting osteopoikilosis. The authors are not aware of previous similar reports. Both conditions are rare, but a causal relationship between them remains unconfirmed.

The long and the short of medullary nailing

One hundred and forty-seven medullary nailings of the femur have been studied to assess a new method of estimating the nail's length preoperatively, using the patient's height.

Clinical value of immunoradiometric assay of thyrotropin for patients with nonthyroidal illness and taking various drugs

Using a two-site immunoradiometric assay, we measured concentrations of thyrotropin (TSH) in serum of 134 clinically euthyroid subjects, 93 patients with nonthyroidal illness, and 80 patients who were being treated with various drugs. Abnormal concentrations of TSH, free thyroxin, and free triiodothyronine, respectively, were recorded in serum of three (3.2%), 19 (20.4%), and 37 (39.8%) of the patients with nonthyroidal illness and in three (3.8%), five (6.3%), and 10 (12.5%) of the patients taking drugs. TSH could be detected in all patients' serum samples. We conclude that, for most patients without thyroid disease, a basal (i.e., unstimulated) measurement of their TSH concentration in serum will indicate their thyroid status more reliably than will assay of free thyroxin or free triiodothyronine.

Clinical value of immunoradiometric assay of thyrotropin for patients with nonthyroidal illness and taking various drugs

Using a two-site immunoradiometric assay, we measured concentrations of thyrotropin (TSH) in serum of 134 clinically euthyroid subjects, 93 patients with nonthyroidal illness, and 80 patients who were being treated with various drugs. Abnormal concentrations of TSH, free thyroxin, and free triiodothyronine, respectively, were recorded in serum of three (3.2%), 19 (20.4%), and 37 (39.8%) of the patients with nonthyroidal illness and in three (3.8%), five (6.3%), and 10 (12.5%) of the patients taking drugs. TSH could be detected in all patients' serum samples. We conclude that, for most patients without thyroid disease, a basal (i.e., unstimulated) measurement of their TSH concentration in serum will indicate their thyroid status more reliably than will assay of free thyroxin or free triiodothyronine.

A modified technique for the fixation of pathologic fractures in the lower femur

Intramedullary nail fixation augmented by the pressure injection of methylmethacrylate was investigated by use of bovine femora. In this technique, the nail is first placed in its final desired position; cement is then injected with a conical-tipped syringe through a distal drill hole into the medullary canal around the nail. This method was compared with the conventional technique of first placing the cement into the medullary canal and then driving the nail into position. Calf femora were used to compare the cement pressures generated, the shear resistance at the bone/cement interface, and the contour of the endosteal cement surface produced by the two cementing techniques. Significantly higher bone/cement interface pressures were generated by the injection of cement. Shear resistance at the bone/cement interface, investigated by push-out tests, revealed no significant difference between the two techniques. Dissolution of the specimens in nitric acid produced a methylmethacrylate cast of the endosteal surface, thus revealing the pattern of cement penetration into endosteal bone. The cement surfaces made by the injection of cement revealed characteristics of superior fixation and penetration compared to those made by the conventional method. The injection of cement for pathologic long-bone fractures is safer than the conventional method, is less susceptible to intraoperative complications, and offers satisfactory fixation.

Cerclage fixation of a fractured humerus in 1775. Fact or fiction?

The description in a French journal in 1775 of cerclage wiring of a humerus has been widely accepted as the first recorded case of internal fixation of a fresh fracture. Retranslation reveals that the operation was not in fact performed, although the subject was of surgical interest at that time.

Septic dislocation of the hip after internal fixation of trochanteric fractures

Infection of the hip joint is described in three patients after nail-plate fixation of trochanteric fractures. This led to subluxation of the joint in one case and to dislocation in the other two. None of the patients walked again. Attention is drawn to the difficulty in diagnosis and the poor prognosis of this uncommon complication of operating for hip fracture.

Impairment of cell-mediated immune responses by infection with Mycobacterium lepraemurium

The effect of chronic infection with Mycobacterium lepraemurium upon cell-mediated immune responses was studied in Lewis rats. Rats infected for 40 to 175 days were completely protected from attempted induction of experimental adjuvant disease, and the severity of experimental allergic encephalomyelitis in leprous rats was markedly attenuated. Full manifestations of each autoimmune disease were expressed in littermate control groups. Skin homograft rejection by infected rats was significantly impaired (P less than 0.001) as was the delayed-type hypersensitivity response to sheep erythrocytes (P less than 0.02). It is suggested that chronic infection with M. lepraemurium exerts a nonspecific inhibitory effect on cell-mediated immunity by perturbation of normal lymphocyte recirculation and by induction of immuno-suppressor cell activity.