The metal-organic chemical vapor deposition growth and propertiesof InAsSb mid-infrared (3-6-μm) lasers and LEDs

We describe the metal-organic chemical vapor deposition (MOCVD) growth of AlAs_1-xSb_x cladding layers and InAsSb-InAs multiple-quantum well (MQW) and InAsSb-InAsP strained-layer superlattice (SLS) active regions for use in mid-infrared emitters. The AlAs_1-xSb_x cladding layers were successfully doped p- or n-type using diethylzinc or tetraethyltin, respectively. By changing the layer thickness and composition of SLSs and MQWs, we have prepared structures with low temperature (<20 K) photoluminescence wavelengths ranging from 3.2 to 6.0 μm. We have made gain-guided injection lasers using undoped p-type AlAs_0.16Sb_0.84 for optical confinement and both strained InAsSb-InAs MQW and InAsSb-InAsP SLS active regions. The lasers and light emitting diodes (LEDs) utilize the semi-metal properties of a GaAsSb(p)-InAs(n) heterojunction as a source for electrons injected into active regions. A multiple-stage LED utilizing this semi-metal injection scheme is reported. Gain-guided, injected lasers with a strained InAsSb-InAs MQW active region operated up to 210 K in pulsed mode with an emission wavelength of 3.8-3.9 μm and a characteristic temperature of 29-40 K. We also present results for both optically pumped and injection lasers with InAsSb-InAsP SLS active regions. The maximum operating temperature of an optically pumped 3.7-μm strained-layer superlattice (SLS) laser was 240 K. An SLS LED emitted at 4.0 μm with 80 μW of power at 300 K     

Progress in protein structure prediction

If protein structure prediction methods are to make any impact on the impending onerous task of analyzing the large numbers of unknown protein sequences generated by the ongoing genome-sequencing projects, it is vital that they make the difficult transition from computational 'gedankenexperiments' to practical software tools. This has already happened in the field of comparative modelling and is currently happening in the threading field. Unfortunately, there is little evidence of this transition happening in the field of ab initio tertiary-structure prediction.     

Basilar membrane nonlinearity and loudness

Loudness matching functions for tones for persons with one shifted-threshold ear (hearing loss and noise-shifted thresholds) and one ear within normal limits were used to derive the presumed basilar membrane (BM) input-output (I/O) function in a normal ear. The comparison was made by assuming that the BM I/O function for the ear with the cochlear threshold shift has a slope of one (a linearized cochlea). The function for the normal ear was derived from the loudness matching function based on this assumption. Comparisons were made for archival basilar membrane data [M. A. Ruggero, N. C. Rich, A. Recio, S. S. Narayan, and L. Robles, J. Acoust. Soc. Am. 101, 2151-2163 (1997)] for chinchilla and archival loudness matches for long-duration tones for persons with various degrees of cochlear hearing loss [F. Miskolczy-Fodor, J. Acoust Soc. Am. 32, 486-492 (1960)]. Comparisons were made also between BM I/O functions and ones derived from loudness matches for persons with unilateral hearing loss simulated by broadband noise. The results show a close resemblance between the basilar membrane I/O function and the function derived from loudness matches for long-duration tones, even though the comparison was between human and chinchilla data. As the degree of threshold shift increases from 40 to 80 dB, the derived BM I/O functions become shallower, with slopes for losses of 60 dB or more falling in the range of values reported for physiological data. Additional measures with short-duration tones in noise show that the slope of the loudness function and the slope of the derived basilar membrane I/O function are associated with the behavioral threshold for the tone. The results for long-duration tones suggest a correspondence between BM displacement and loudness perception in cases of recruitment, but the relation between the degree of loss and the amount of BM compression and the relation between signal duration and compression suggests that other factors, such as the neural population response, may play a role.     

P-selectin blockade is beneficial after uncontrolled hemorrhagic shock

OBJECTIVE: Increased intra-abdominal pressure (IAP) compromises cardiopulmonary function and visceral perfusion. Our goal was to characterize acute changes in these subsystems associated with operative abdominal decompression. PATIENT POPULATION: A series of 11 consecutive injured patients monitored with a pulmonary artery catheter and nasogastric tonometer in whom operative decompression was performed. Indications for decompression included oliguria or progressive acidosis despite aggressive resuscitation in the presence of elevated IAP (>25 mm Hg). MAIN OUTCOME MEASURES: Studied hemodynamic variables included pulmonary artery occlusion pressure (PAOP), right ventricular end-diastolic volume index (RVEDVI), and cardiac index (CI). Pulmonary variables included shunt fraction (Qs/Qt) and dynamic compliance (Cdyn). Visceral perfusion was assessed using hourly urine output 4 hours before and after decompression (UOP) and gastric intramucosal pH (pHi). Mean values before and after decompression were compared using the paired t test. Linear regression and Fisher's z transformation were used to evaluate the relationships between RVEDVI, PAOP, CI, and IAP. IAP was transduced via bladder pressures. Significance was defined as p < 0.05. Data are expressed as means+/-SD. RESULTS: IAP decreased with decompression (49+/-11 to 19+/-6.8 mm Hg; p < 0.0001). RVEDVI improved independent of CI and correlated better (p < 0.01) with CI (r =0.49, p=0.04) than PAOP did (r=-0.36, p=0.09). PAOP correlated significantly with IAP (r=0.45, p=0.04). Decompression resulted in significant improvements in Qs/Qt, Cdyn, UOP, and pHi. CONCLUSION: Abdominal decompression in patients with increased IAP improves preload, pulmonary function, and visceral perfusion. Elevated IAP has important effects on PAOP, which makes the PAOP an unreliable index of preload in these patients.     

Effects of hydrotherapy on pressure ulcer healing

We have earlier reported a higher Fcgamma-receptor (FcgammaR)-mediated generation of reactive oxygen species, measured as luminol-enhanced chemiluminescence (CL) from peripheral neutrophils in adult periodontitis patients. The aims of this study were to confirm our previous results and to elucidate the mechanism of this phenomenon by measuring CL in parallel with the intracellular production of hydrogen peroxide, after stimulation with opsonized bacteria. To determine whether the higher CL was associated with altered responsiveness to priming, the cells were preincubated with tumor necrosis factor alpha (TNFalpha) and lipopolysaccharide (LPS). While CL was significantly higher in subjects with periodontitis, there was no difference in hydrogen peroxide production between the patients and the controls, indicating that the hyperreactivity is related to the generation of other oxygen species than H2O2 and/or to processes in the outer cell membrane. The responsiveness to priming with LPS on CL was slightly but not significantly higher in the periodontitis group, suggesting that priming could be of value for distinguishing subjects with periodontitis. When assaying intracellular production of H2O2, TNFalpha and LPS had both a priming and an activating effect. There were no significant differences between the two groups. In conclusion, this study shows a higher FcgammaR-mediated CL of peripheral neutrophils from adult patients with periodontitis, thus confirming our earlier results. The hyperreactivity seems to be related to the outer cell membrane or to oxygen species other than H2O2.     

Smith-Lemli-Opitz syndrome: phenotypic extreme with minimal clinical findings

The effect of spine venom from the crown-of-thorns starfish (Acanthaster planci) on drug-metabolizing enzymes in rat liver was studied. The spine venom was prepared by saturation of spine homogenate with ammonium sulfate and the protein fraction precipitating 50% saturation was used as venom B. Venom A was the protein precipitated between 50 and 100% saturation. When venom B (100-200 mg/kg) was given to rats, liver microsomal GSH S-transferase and cytochrome P450 activities decreased while cytosolic GSH S-transferase activity was not changed. The decrease in these microsomal enzyme activities was seen from 12 hr to 24 hr after giving 100 mg/kg of venom B. Rats given venom A died, suggesting an involvement of the lethal factor in venom A. The data showed that the spine venom B from A. planci depressed microsomal GSH S-transferase and cytochrome P450 activities in rat liver and that this venom was distinct from the lethal factor of the spine venom.     

High-dose therapy with peripheral blood stem cell (PBSC) support using an innovative mobilization regimen in patients with high-risk primary or chemoresponsive metastatic breast cancers

BACKGROUND: Epidemiologic studies are necessary to determine the prevalence of allergic diseases. This varies widely depending on allergen preparations and patients studied. OBJECTIVE: To investigate the prevalence of atopic disease, skin test reactivity, total and specific IgE to common allergens, and other variables in a sample of students from Málaga, southern Spain. METHODS: Three hundred sixty-five students (age 17.9 +/- 1.18) were interviewed by an allergist. Skin prick tests were performed with Dermatophagoides pteronyssinus, Artemisia vulgaris, Plantago lanceolata, Chenopodium album, Olea europaea, Phleum pratense, Parietaria judaica, Cynodon dactylon, Alternaria tenuis, and cat dander. Total and specific IgE to D. pteronyssinus, Olea, and Parietaria were determined. RESULTS: Of all subjects studied, 19.9% suffered from rhinoconjunctivitis, 4.1% rhinoconjunctivitis plus asthma, 3.1% asthma alone, and 0.8% atopic dermatitis; 46.4% had a positive skin test to at least one allergen (28.2% to D. pteronyssinus, 20.4% to Olea, 13.8% to Phleum); and 43% had total IgE > 100 kU/L and 44.7% a family history of atopy. Allergic symptoms were strongly associated with skin test positivities and family allergic history. Patients with asthma or skin prick test positive had higher total IgE values than others (P < .01). There was a significant correlation between specific IgE values and wheal size in skin test. CONCLUSIONS: Our findings confirm the high prevalence of atopic diseases, and the close relationship of skin tests reactivity (or presence of specific IgE) to allergens with symptoms of asthma and rhinitis. The presence of a family history of allergic diseases influences the development of positive skin tests and atopic illness. Dermatophagoides pteronyssinus and pollen of Olea europaea were found to be the most common allergens.     

Gelatinase B and A expression after laser in situ keratomileusis and photorefractive keratectomy

OBJECTIVE: To compare the expression of gelatinases in the corneal epithelium and stroma after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). METHODS: Rabbit eyes were treated with LASIK (n=11), PRK (n=12), or corneal flap construction (n=12); 4 eyes served as unwounded controls. Zymography was performed on the central epithelium and the stroma 1, 3, and 7 days after surgery to determine the expression of gelatinases. RESULTS: Epithelial expression of gelatinase B in the LASIK group (0%-25%) was lower than that in the PRK group at all time points (50%-100%) and was identical to the corneal flap group. Stromal expression of gelatinases A and B was similar after LASIK and PRK, but was minimal after corneal flap construction at all time points. Epithelial expression of gelatinase A was similar for the first 3 days after LASIK and PRK but not thereafter. CONCLUSIONS: Gelatinase B epithelial expression was up-regulated after PRK but not after LASIK. Gelatinase B stromal expression was up-regulated after both procedures. CLINICAL RELEVANCE: Differences in wound healing and subepithelial scarring after these 2 procedures may be related to gelatinase B.