O-O bond cleavage via electrochemical reduction of a side-on peroxo dicopper model of hemocyanin.

The redox properties of the µ-η2:η2 peroxo complex [Cu2(H6M4h)(O2)]2+ were elucidated. This study constitutes the first full electrochemical and spectroelectrochemical characterization of a side-on peroxo Cu2:O2 bioinorganic model complex. The peroxo complex is irreversibly reduced in a two-electron process localized on the peroxo ligand triggering the cleavage of the O-O bond.

Piperazine-based CCR5 antagonists as HIV-1 inhibitors. II. Discovery of 1-[(2,4-dimethyl-3-pyridinyl)carbonyl]-4- methyl-4-[3(S)-methyl-4-[1(S)-[4-(trifluoromethyl)phenyl]ethyl]-1-piperazinyl]- piperidine N1-oxide (Sch-350634), an orally bioavailable, potent CCR5 antagonist.

Truncation of the original piperidino-2(S)-methyl piperazine lead structure 2, from a family of muscarinic antagonists, gave compound 8 which has improved selectivity for the HIV-1 co-receptor CCR5 over muscarinic receptors. Further optimization for pharmacokinetic properties afforded Sch-350634 (1), a prototypical piperazine-based CCR5 antagonist, which is a potent inhibitor of HIV-1 entry and replication in PBMCs. The title compound (1) has excellent oral bioavailability in rat, dog, and monkey.

Differential production of interleukin 10 during human immunodeficiency virus infection.

Interleukin 10, a product of T and B cells and monocytes, displays many Th2-like properties through inhibition of Th1 cell functions. Interleukin 10 is thought to play a major role in the immune dysfunction seen in HIV-infected individuals. In this study, we evaluated in detail the production of IL-10 during HIV infection. Although the constitutive production of IL-10 did not differ in PBMCs from healthy donors and HIV-infected individuals, IL-10 was differentially produced in response to polyclonal activators. The overall plasma IL-10 levels were similar in 32 controls and 67 patients at different stages of the disease and receiving different antiretroviral drugs. However, patients with low CD4 T cell count (< 200/mm3) secreted approximately three-fold more IL-10 than did patients with high CD4 T cell count (> 500/mm3). Competitive/quantitative PCR revealed similar levels of mRNA expression in PBMCs from controls and HIV-infected individuals. In vitro HIV infection rapidly and transiently induced IL-10 production in PBMCs and monocytes, and the low level of endogenously secreted IL-10 failed to inhibit HIV replication in acutely infected monocytes. On the other hand, HIV infection of selected CD4+ T cell clones generated in a Th1- or Th2-like environment, differentially up-regulated IL-10 production, with significantly higher production by Th2 clones. Together, our data indicate that IL-10 production is more complex than previously thought, and may depend on several factors such as producer cells, nature of the stimuli, as well as viral isolates.

Cardiovascular response to acute and chronic endotoxemia in an awake, volume-resuscitated, canine model.

The cardiovascular response to endotoxemia was evaluated in an awake, intravascular volume-resuscitated canine model. The animals were chronically instrumented for ultrasonic crystal dimension analysis and pressure measurements of the left ventricle (LV), aorta, right atrium (RA), and pulmonary artery (PA) and for cardiac output (CO) measurement. Lipopolysaccharide (Escherichia coli 011:B4) (LPS) was administered intravenously either as an acute, high dose bolus (5 mg/kg; n = 5), a high dose bolus after complete beta-blockade with propranolol (n = 3), or a chronic, low dose infusion (5 micrograms/kg/h; n = 7). Relative to baseline values, cardiac contractility was increased after acute high dose LPS bolus, however this effect was negated by beta-blockade. Chronic, low dose LPS infusion produced an increase in cardiac contractility at 1 h, a return to baseline by 4 h, and maximal contractile depression by 24 h. No change was seen in LV compliance after the high dose LPS bolus. The LV end diastolic volume was decreased by the high dose LPS bolus. This change was blocked by propranolol administration. Chronic LPS administration was accompanied by a decrease in LV compliance and an increase in LV end diastolic volume. Other cardiovascular indices (heart rate, CO, systemic vascular resistance) changed in a fashion similar to human sepsis. These findings confirm that endotoxemia in conscious canine subjects causes changes in cardiovascular function similar to that seen in human and animal models of sepsis. This study also allows us to explain some of the discrepancies between earlier studies of human sepsis and animal models in which the appropriate clinical conditions and an intact neuro-endocrine axis were not maintained.

Age differences in using a rapid step to regain balance during a forward fall.

BACKGROUND: Earlier studies showed that healthy old adults have substantially reduced abilities to develop joint torques rapidly. We hypothesized that this age decline would reduce abilities to regain balance once a forward fall is underway. The present study examined whether aging in fact reduces ability to regain balance by taking a single, rapid step upon release from a forward lean. METHODS: Ten young (mean age 24.3 yr) and ten old (72.8 yr) healthy males were released from a forward-leaning position and instructed to regain standing balance by taking a single step forward. Lean angle was successively increased until a subject failed to regain balance as instructed. Lower extremity motions and foot-floor reactions were measured during the responses. Total response time was divided into reaction, weight transfer, and step times. RESULTS: At small lean angles, responses of old subjects were similar to those of the young. However, the mean maximum lean angle from which old could regain balance as instructed was significantly smaller than that for young (23.9 vs 32.5 deg, p < .0005). Within each age group, maximum lean angle correlated strongly with weight transfer time and step velocity. CONCLUSIONS: Substantial age-related declines in the ability to regain balance by taking a rapid step exist among healthy adults when the time available for recovery is short. The source of the decline seems largely to lie in the decrease with age of maximum response execution speed rather than in the sensory or motor programming processes involved in response initiation.

Age and gender differences in single-step recovery from a forward fall.

BACKGROUND: Previous work has found that healthy older men were significantly less able than young male adults to recover balance by taking a single rapid step upon sudden release from forward leans. In light of the higher rates of falls and fall-related injuries among older women compared to older men, we hypothesized that healthy older women would perform more poorly than either female young adults or older men in this test of abilities to recover balance rapidly. METHODS: Ten young (mean age 25.0 years) and 10 older (73.7 years) healthy women were released from forward leans and instructed to regain standing balance by taking a single step forward. The lean angle was incrementally increased from its smallest value, approximately 14 degrees, until the subject failed to regain balance as instructed. Lower extremity kinematics were measured, and findings were compared with those of the earlier study of healthy young and old men. RESULTS: Five of the 10 older women could not recover balance with a single step after release from the smallest of the imposed forward leans. For the 5 older women who succeeded in recovering as instructed from at least one lean, the mean maximum lean angle was significantly smaller than that for young women (16.2 degrees vs 30.7 degrees, p < .001) or older men (16.2 degrees vs 23.9 degrees, p = .014). In contrast, there was no significant difference in mean maximum lean angle between female and male young adults. CONCLUSIONS: Healthy older women, compared to either young women or older men, were significantly less able to recover balance by taking a single rapid step during a forward fall. The decreased abilities of older women appeared to result from limitations in the maximum speeds at which they moved their swing foot during recovery.

The wet child.

Urinary incontinence is one of the most frequent problems seen in pediatric urology. Although there can be serious structural problems that produce wetting, most of the children seen will have nonstructural causes for their incontinence. A systematic approach and persistence with therapy should result in resolution of the problem in most instances.

Age and gender differences in peak lower extremity joint torques and ranges of motion used during single-step balance recovery from a forward fall.

Previous studies have found substantial age and gender group differences in the ability of healthy adults to regain balance with a single step after a forward fall. It was hypothesized that differences in lower extremity joint strengths and ranges of motion (ROM) may have contributed to these observed differences. Kinematic and forceplate data were therefore used with a rigid-link biomechanical model simulating stepped leg dynamics to examine the joint torques and ROM used by subjects during successful single-step balance recoveries after release from a forward lean. The peak ROM and torques used by subjects in the study were compared to published estimates or measured values of the available maxima. No significant age or gender group differences were found in the mean ROM used by the subjects for any given initial lean angle. As initial lean angle increased, larger knee ROM and significantly larger hip ROM were used in the successful recoveries. There were substantial gender differences and some age group differences in peak lower extremity joint torques used in successful recoveries. Both young and older females often used nearly maximal joint torques to recover balance. Subjects' maximum joint strengths in plantarflexion and hip flexion were not good predictors of single-step balance recovery ability, particularly among the female subjects.

Acoustic streaming: comparison of low-amplitude linear model with streaming velocities measured by 32-MHz Doppler.

The pressure gradient along the ultrasonic beam results in medium streaming. Following Nyborg's analysis of the Navier-Stokes equation, Wu and Du developed an approximate solution for the streaming velocity generated by flat and weakly focused transducers. We have modified their solution of the Poisson equation by directly deriving the Dirichlet boundary conditions to be applied for this type of equation. Our numerical results (for the linear case) were about one half smaller for flat and weakly focused on Gaussian beam transducers compared to the results by Wu and Du. The theoretical calculations were verified using a purpose-designed 32-MHz pulsed Doppler unit. The applied average acoustic power was changed from 1 microW to 6 mW, the burst width was 0.5 microseconds and the pulse repetition frequency was 32 kHz. The experiments were done on 4-mm-diameter flat and focused (focal distance = 8 and 12 mm) transducers. The streaming was measured along the ultrasonic beam from 0-20 mm; at all positions, the maximum Doppler frequency was estimated from the recorded spectra. Streaming was induced in a solution of water and corn starch. The experimental results showed that, for a given acoustic power, the streaming velocity was independent of the starch density in water changed from 0.3-40 g of starch in 1 l of distilled water. For applied acoustic powers, the streaming velocity changed linearly from 0.2-40 mm/s. Both the theoretical solutions for plane and focused waves and the experimental results were in good agreement.

Elderly ambulatory care patients' knowledge about drugs.

The extent of knowledge that elderly ambulatory clinic patients possessed about their maintenance prescription and nonprescription medications was determined using 17 selected questions. Information was obtained by using structured interviews from 100 subjects, 65 years of age or older, selected from a general medicine clinic using the simple two-stage cluster sampling method. The medical charts and various medication teaching manuals were used as criteria to determine whether or not the questions were answered correctly. The questions bout adverse reactions, nonprescription medications to avoid, and activities to avoid or perform with caution were answered correctly less than 30% of the time. Thus, practitioners should not assume that elderly ambulatory patients on maintenance drug therapy possess sufficient knowledge to use their medications safely and effectively.

Matrix metaloproteinases activity during the evolution of hypoxic-ischemic brain damage in the immature rat. The effect of 1-methylnicotinamide (MNA).

Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that degrade the extracellular matrix and carry out key functions during brain development. Apart from a physiological role, excessive activation of MMPs in brain tissue has been postulated to represent a pathway for cell death arising from ischemia. To evaluate the possible involvement of MMPs in the perinatal brain asphyxia, we exposed 7-day-old rats to hypoxia-ischemia (HI). Unilateral HI was administered by ligation of the common carotid artery followed by hypoxia (7.4% O2/92.6% N2) for 65 minutes. This insult is known to produce brain damage confined to the cerebral hemisphere ipsilateral to the arterial occlusion in > 90% of animals. HI resulted in a significant elevation of MMP-2 and MMP-9 activity in the ipsilateral forebrain. The maximum activation was found at 48 hours and 7-14 days after the insult. These results suggest that early and late induction of MMPs may play a role in neuronal death as well as in repair processes. The treatment of animals subjected to HI with 1-methylnicotinamide (MNA), the anti-inflammatory agent, led to the inhibition of MMP-9 in an acute phase of ischemic damage and to the activation of MMP-2 in the later stages after injury. The timing of MMPs modulation by MNA may indicate its possible therapeutic implications.

Mass spectrometric investigation of dissociative ionization of toxic gases by electrons at 20-1000 eV.

Measurements of the dissociative ionization cross-sections of CO, CO2, NO and N2O molecules for electrons from 20 up to 1000 eV were performed. Total collection of ions was achieved by using a specially constructed cycloidal mass spectrometer, an ion source without slit and a collector with large area. In that open ion source the effusion molecular beam formed by a capillary was crossed by the electron beam. Owing to such parameters of the mass spectrometer the mass discrimination effects were reduced. At the ionization of CO molecules, the ions CO+, C+, O+ and CO2+ were registered; at CO2, the ions CO2+, CO+, O+, C+ and CO2(2)+; at NO, the ions NO+, N+, O+ and NO2+; at N2O, the ions N2O+, NO+, N2+, O+, (N+,N2(2)+) and N2O2+. The relative values of the partial cross-sections were normalized to the absolute total ionization cross-sections obtained by Rapp and Englander-Golden.

Dorsal cortex lesions impair habituation in turtles (Chrysemys picta).

Two experiments investigated habituation in painted turtles (Chrysemys picta). In the first, turtles were given lesions of the dorsal cortex or sham lesions and then trained on a restraint. Although the sham-lesioned turtles learned to tolerate the restraint, the lesioned animals continued to struggle against it. Thus dorsal cortex lesions disrupted habituation to restraint. In order to test habituation to a looming stimulus in a second experiment, all animals were habituated to the restraint before surgery. Postoperatively they continued to be habituated to the restraint. The looming stimulus was a circular shadow that enlarged suddenly on a screen in front of the turtle. It was presented 5 times per day for 15 days. Between-day or long-term habituation was impaired by dorsal cortex lesions.

Cystic dysplasia of the rete testis: a benign congenital lesion associated with ipsilateral urological anomalies.

PURPOSE: Cystic dysplasia of the rete testis is a benign congenital lesion that can mimic testicular cancer. We report 6 cases, review the literature, discuss the embryological etiology and make management recommendations. MATERIALS AND METHODS: The records and pathology reports of 6 boys presenting with cystic dysplasia of the rete testis at 5 institutions were reviewed, as was the relevant literature. RESULTS: Of the 6 cases 5 presented as scrotal masses in previously healthy boys and 1 as an abdominal mass in a newborn with multiple congenital anomalies. One patient had been followed from birth for a multicystic dysplastic kidney and 4 were found to have an ipsilateral absent kidney during evaluation. Development of the contralateral side was normal in most cases. CONCLUSIONS: Cystic dysplasia of the rete testis is an unusual, benign congenital lesion that can mimic testicular cancer in presentation. The presence of ipsilateral renal anomalies, particularly renal agenesis, can suggest cystic dysplasia of the rete testis in the differential diagnosis preoperatively. Even if cystic dysplasia of the rete testis is suspected, we recommend inguinal exploration and early control of the spermatic cord in the event that neoplasia is identified. If possible, the goal of preserving as much normal testicular parenchyma as possible is desirable. Long-term followup for possible recurrence is recommended, particularly after local excision.

Application of immunomagnetic beads in combination with RT-PCR for the detection of circulating prostate cancer cells.

Recently published protocols using Reverse Transcriptase Polymerase Chain reaction (RT-PCR) for prostate specific antigen (PSA) provide a sensitive means for detecting circulating prostate cancer cells. Attempts to use these assays for staging of prostate cancer have produced conflicting results. As a first step towards rectifying these discrepancies, a modified immunobead-RT-PCR assay capable of detecting as few as 10 prostate cancer cells in 8cc of blood was developed. This 10 fold increase in sensitivity was achieved in part by introducing two target cell enrichment steps. As a model system to assess sensitivity of the modified assay, template RNA was extracted from PSA positive human carcinoma cells suspended in human blood and isolated with immunomagnetic beads following incubation with an epithelium specific antibody. After 45 cycles of PCR, product from as few as 10 target cells could be readily detected when displayed on a 2% agarose gel stained with SYBR Green fluorescent dye. The identity of amplified DNA fragments was confirmed by Southern blot hybridization. When applied to blood samples from patients with proven metastatic disease, the immuno-bead RT-PCR assay was successful in detecting circulating PSA positive epithelial cells, suggesting this assay may be useful for assessment of disease progression or recurrence.

SCH-C (SCH 351125), an orally bioavailable, small molecule antagonist of the chemokine receptor CCR5, is a potent inhibitor of HIV-1 infection in vitro and in vivo.

We describe here the identification and properties of SCH-C (SCH 351125), a small molecule inhibitor of HIV-1 entry via the CCR5 coreceptor. SCH-C, an oxime-piperidine compound, is a specific CCR5 antagonist as determined in multiple receptor binding and signal transduction assays. This compound specifically inhibits HIV-1 infection mediated by CCR5 in U-87 astroglioma cells but has no effect on infection of CXCR4-expressing cells. SCH-C has broad and potent antiviral activity in vitro against primary HIV-1 isolates that use CCR5 as their entry coreceptor, with mean 50% inhibitory concentrations ranging between 0.4 and 9 nM. Moreover, SCH-C strongly inhibits the replication of an R5-using HIV-1 isolate in SCID-hu Thy/Liv mice. SCH-C has a favorable pharmacokinetic profile in rodents and primates with an oral bioavailability of 50-60% and a serum half-life of 5-6 h. On the basis of its novel mechanism of action, potent antiviral activity, and in vivo pharmacokinetic profile, SCH-C is a promising new candidate for therapeutic intervention of HIV infection.