Enhanced radiative recombination and suppressed Auger process in semipolar and nonpolar InGaN/GaN quantum wells grown over GaN nanowires.

The mechanism behind the improved light emission properties of semipolar and nonpolar InGaN/GaN multiple quantum wells (MQWs) conformally grown over n-GaN nanowires (NWs) was studied using variable-temperature photoluminescence and time-resolved photoluminescence (TRPL). A reduced internal polarization electric field was found to account for the observed enhancement in the radiative recombination rate and internal quantum efficiency of the MQWs on NWs. Additionally, the excitation-dependent TRPL results indicate a significantly depressed Auger recombination in MQWs grown on NWs that can be attributed to the feature of ultralow dislocation density of the MQWs grown over GaN nanostructures.

Oxamniquine versus niridazole for treatment of uncomplicated Schistosoma mansoni infection.

One hundred sixteen male patients with uncomplicated Schistosoma mansoni infection were randomized to treatment with oxamniquine (20 mg/kg a day for 3 days) or niridazole (15 mg/kg a day for 8 days) in an in-hospital study. Fifty-four patients were treated with oxamniquine; no serious drug side effects were noted. Twenty-six percent of children 16 years old and younger were cured, while 85% of adults were cured. Egg reduction was 89%. Sixty-two patients were treated with niridazole; four patients (one child and three adults) had serious side effects which necessitated discontinuing the drug. Seventy-one percent of children and 84% of adults were cured. Egg reduction was 84%. Minor clinical side effects occurred during therapy with both drugs (26% with oxamniquine, 48% with niridazole) but cleared after completion of therapy. Niridazole is the more effective drug for the child with uncomplicated Schistosomiasis mansoni, but oxamniquine is advised for the adult with this disease.

Safety and immunogenicity of a recombinant hepatitis B vaccine in patients infected with Schistosoma mansoni.

Thirty Egyptian males, 8-31 years of age, with active Schistosoma mansoni infection and negative serologic tests for hepatitis B markers, were vaccinated with a recombinant hepatitis B vaccine (Merck's Recombivax). The vaccine was given intramuscularly in the deltoid region in three 10 micrograms doses at 0, 1, and 6 months. All patients were treated with praziquantel 2 months after the first vaccination. Sera were collected every 2 months for 12 months and tested for anti-HBs using a quantitative ELISA technique. There were no side reactions except for mild local soreness at the injection site in 3 patients. At 12 months, all subjects seroconverted (antibody levels greater than 10 mIU/mL); 24 patients (80%) developed antibody levels greater than 1,000 mIU/mL. As with a plasma-derived vaccine, antibody levels were negatively correlated with increasing spleen size. A recombinant hepatitis B vaccine was safe and immunogenic when given to patients with schistosomiasis mansoni.

Treatment of schistosomiasis mansoni with oxamniquine--five years' experience.

During a 5-year period (1975-1980), 171 male patients aged eight to 58 years infected with Schistosoma mansoni have been treated with oxamniquine on an in-hospital basis. The patients comprised three clinical groups--uncomplicated S. mansoni infection, colonic polyposis due to S. mansoni, and hepatic decompensation due to S. mansoni--all with active infection. After treatment all patients were observed for 12 weeks then evaluated for cure. In the uncomplicated group 40 of 73 children (55%) and 39 of 45 adults (87%) were cured. In the polyps group 24 of 29 patients (83%) were cured and in the decompensated group all 24 patients were cured. The only side effect was a febrile reaction occurring in 65 patients (38%) 3-4 days after treatment was started. This 5 years' experience showed that oxamniquine results in a low cure rate in children but is effective in adults with uncomplicated S. mansoni. In patients with colonic polyposis oxamniquine is safe and well tolerated as initial therapy, particularly in the very ill, debilitated patient. Oxamniquine is clearly the drug of choice in patients with decompensated liver disease and active S. mansoni infection.

Improved diagnostic performance of the circulating antigen assay in human schistosomiasis by parallel testing for circulating anodic and cathodic antigens in serum and urine.

Serum and urine levels of two Schistosoma circulating antigens, the circulating anodic antigen (CAA) and the circulating cathodic antigen (CCA), were determined by monoclonal antibody-based enzyme-linked immunosorbent assays in 56 Egyptian patients infected with S. mansoni and in 12 patients infected with both S. mansoni and S. haematobium. Both CAA and CCA could be specifically demonstrated in 82% and 88% of the serum samples and in 88% and 87% of the urine samples, respectively. While complete specificity was maintained, sensitivity was increased to a range of 91-98% by parallel use of the two circulating antigen assays, i.e., an individual with a positive titer for at least one of the assays was considered to be infected. A combination of CAA and CCA determinations in urine samples only resulted in a sensitivity of 94%. However, the highest sensitivity was achieved when the serum-CCA assay was combined with the urine-CCA assay (98%) or with the urine-CAA assay (97%). Sensitivity could not be increased further by combining more than two tests. A significant correlation was demonstrated between the level of circulating antigen and the number of parasite eggs in feces in each of the four assays. In addition, the levels of CAA and CCA in serum and urine were significantly correlated with each other. Our results indicate that diagnosis of schistosome infections by detection of circulating antigens can be significantly improved by parallel testing for multiple antigens.

Immunogenicity of hepatitis B vaccine in patients infected with Schistosoma mansoni.

Because dual infection with Schistosoma mansoni and hepatitis B may lead to severe liver disease, populations living in schistosomiasis-endemic areas might benefit if effectively immunized against hepatitis B. To determine whether a plasma-derived hepatitis B vaccine is immunogenic in patients with schistosomiasis, 32 individuals infected with S. mansoni were given three 20-micrograms doses of Heptavax-B vaccine and treated with praziquantel. Antibody to hepatitis B surface antigen developed in 90.6% of the study subjects after three doses of vaccine. Five patients (15.6%) had a weak response to the vaccine, and three patients (9.4%) failed to develop antibody. A weak or failed response to the vaccine was significantly associated with the presence of hepatosplenomegaly. A plasma-derived vaccine is immunogenic for persons infected with S. mansoni; however, vaccine response is diminished in hepatosplenic schistosomiasis.

Immunogenicity of recombinant hepatitis B vaccine among infants of mothers with active schistosomiasis.

A study of the immunogenicity of a recombinant hepatitis B vaccine was conducted among 385 Egyptian infants, 191 (49.6%) of whom were born to mothers with moderately active Schistosoma mansoni infection (mean egg count = 224 eggs/g of feces). All mothers were seronegative for hepatitis B surface antigen (HBsAg) and hepatitis B e antigen. Infants were vaccinated with a 2.5-microg dose of this vaccine, given along with diphtheria, tetanus, and pertussis (DTP) vaccine, at the ages of two, four, and six months. Serum samples taken from each infant at nine months of age were tested for HBsAg, antibody to hepatitis B core antigen, and quantitatively for antibody to hepatitis B surface antigen (anti-HBs). There was no significant difference (P = 0.1) between anti-HBs titers in infants of S. mansoni-infected mothers (mean = 539 mIU/ml) and in infants of noninfected mothers (mean = 377 mIU/ml). This study shows that there was no apparent effect of maternal schistosomiasis infection on the immune response of these infants to vaccination.

Short-course norfloxacin and trimethoprim-sulfamethoxazole treatment of shigellosis and salmonellosis in Egypt.

In a double-blind clinical study, 109 adult Egyptian patients infected with Shigella spp. and 45 infected with Salmonella spp. were randomly assigned to three treatment groups: 1) norfloxacin in a single 800-mg dose, 2) norfloxacin, 400 mg twice a day for three days, and 3) trimethoprim (160 mg)-sulfamethoxazole (800 mg) (TMP-SMX), twice a day for three days. Among Shigella-infected patients, diarrheal symptoms had resolved in 86-97% and bacteriologic failure (repeat positive stool culture) occurred in only two patients five days after the start of the three treatment regimens. Among Salmonella-infected patients, diarrheal symptoms had resolved in 76-82% of patients and bacteriologic failure was common (18-36%) five days after the start of therapy. These data indicate that short-course therapy with either norfloxacin or TMP-SMX can be effectively used to treat shigellosis in adults in developing countries. However, for uncomplicated Salmonella spp. infection, short-course therapy with norfloxacin and TMP-SMX may not lead to a rapid resolution of symptoms or consistently eliminate this enteropathogen.

Biochemical characterisation of human isolates of Blastocystis hominis.

SDS-PAGE and iso-enzyme analysis of 11 human isolates of Blastocystis hominis revealed at least two variants with different polypeptide patterns and two zymodemes, respectively. This is the first iso-enzyme and the second protein analysis to indicate strain differences in B. hominis.

Hydrogen ion excretion and urine osmolality in patients with obstructive uropathy secondary to Schistosoma haematobium.

Sixty-one patients with urinary schistosomiasis were studied to determine the effects of obstruction and bacteriuria on renal function. 39 (12 with bacteriuria) had demonstrable obstruction and 22 (5 with bacteriuria) had no obstruction. Total hydrogen ion excretion (T.H.+) for obstructed patients with sterile urine did not differ from that in controls; patients with bacteriuria with and without obstruction had a significantly lower T.H.+ (all P values less than 0.05). Obstructed patients (with or without bacteriuria) had significant impairment of maximal (U max) and minimal (U min) urine osmolality. Patients with bilateral obstruction and bacteriuria had a significantly lower U max (P less than 0.01 than obstructed patients without bacteriuria. The T.H.+ is mainly associated with bacteriuria but that the effects of unilateral or bilateral obstruction and bacteriuria on urine osmolality are additive. These abnormalities are usually corrected after therapy.

Efficacy of medical treatment of schistosomal obstructive uropathy as determined by 131I-Hippuran renography.

Ten male patients with obstructive uropathy secondary to Schistosoma haematobium and with associated bacteriuria were evaluated with serial urograms, renograms and renal function tests (endogenous creatinine clearance, maximal urinary concentration and total hydrogen ion excretion) before and after medical treatment. The mean duration of follow-up was 4.2 months. Significant improvement was observed in the renograms and the renal function tests while the degree of obstructive uropathy as determined by urography remained essentially unchanged. Thus the renogram can be a more sensitive test for evaluating the efficacy of treatment in patients with schistosomal obstructive uropathy.