Expression of the Rh/RhAG complex is reduced in Mi.III erythrocytes.

BACKGROUND AND OBJECTIVES: Miltenberger blood group antigen subtype III (Mi.III) is characterized by expression of a glycophorin B-A-B hybrid (Gp.Mur) on the erythrocyte surface. The two alleles of glycophorin B are substituted with the B-A-B hybrid alleles in homozygous Mi.III (Mi.III(+/+)), and thus, Mi.III(+/+) erythrocytes lack glycophorin B (GPB) and express Gp.Mur only. Because GPB is a major component of the Rh complex on RBCs, in this study, we explored how the absence of GPB might affect Rh expression in Mi.III RBCs. MATERIALS AND METHODS: (1) Mi.III+ RBCs were serologically identified and further differentiated their homozygosity or heterozygosity by immunoblot or direct sequencing. (2) RhD and RhCcEe mRNA was cloned, and their sequences analysed. (3) The expression levels of Rh antigen, Rh-associated glycoprotein (RhAG) and the U antigen in MI.III vs. non-Mi.III RBCs were assessed by flow cytometry and Western blot. RESULTS: Compared with the non-Mi.III samples, the surface expression of the Rh antigen was reduced to 76·4% in Mi.III(+/+) RBCs and 93·6% in Mi.III(+/-). RhAG expression was also significantly reduced in Mi.III(+/+), but not in Mi.III(+/-). The U antigen expression in Mi.III(+/-) was only 14·9% relative to the control RBCs, while GPB was half the level of the controls. The mRNA sequences of Rh polypeptides from Mi.III+ samples were identical to the NCBI reference sequences. CONCLUSION: Substitution of GPB with Gp.Mur significantly reduced the expression of Rh antigen and RhAG on the Mi.III(+/+) erythrocyte membrane. The Mi.III phenotype is predicted to induce considerable structural variations within the band 3/Rh-associated macrocomplexes.

Bacterial community changes with N'-N' dimethylforamide (DMF) additives during polycyclic aromatic hydrocarbons (PAH) biodegardation.

This study examined the changes in the bacterial community during biodegradation of polycyclic aromatic hydrocarbon (PAH) substrate when N'-N' dimethylformamide (DMF) was added. The microbial populations that biodegrade the PAH substrate were assessed by Fluorescence in-situ hybridization (FISH) and changed from 49.45% Archaea and 49.15% Bacteria to 42.00% Archaea and 51.78% Bacteria when the PAH was supplemented with DMF. Nine microorganisms were classified as Gram-negative alpha-, beta- and gamma-Proteobacteria bacteria during biodegradation of PAH alone by the Biolog system. Incentive eleven microorganisms obtained from the PAH-DMF mixed substrate were found to be beta-, gamma-Proteobacteria bacteria, high G+C Gram-positive bacteria (HGC), low G+C Gram-positive bacteria (LGC) and there was even one Deinococcus-Thermus strain; this indicates greater biodiversity. The numbers in the Pseudomonad group were as high as 10(5)-10(6) CFU ml(-1), suggesting that this group plays an important role in PAH biodegradation. Community-Level Physiological Profiling (CLPP) and physiological characterization were different in the PAH biodegradation process with and without DMF. Utilization of the 95 carbon sources from the Biolog GN2 microtiter plate was greater during PAH biodegradation when PAH is present alone compared to that in the presence of DMF. The range of enzymatic activities during PAH biodegradation was lower in the presence of DMF. These results show that DMF should be used with caution when PAH is a substrate during laboratory or pilot biotreatability studies.

A bioelectrode for penicillin detection based on gluten-membrane-entrapped microbial cells.

A bioelectrode for penicillin detection was established using gluten membrane in which cells of Escherichia coli harbouring the plasmid pUC18 coding for penicillinase synthesis were entrapped. For the entrapment preparation, lyophilized cells were mixed with gluten solution during the formation of gel, and the resultant gel was hardened by the addition of oxidized starch. The immobilization procedure employed an inexpensive base material and avoided the use of purified enzyme. When the membrane with a thickness of 30 microm and a cell content of 33% (w/w) was used, the steady response of the bioelectrode to increasing concentrations of penicillin G buffered with 0.025 M phosphate was linear over the range of 1-16 mM. The response time was less than 3 min. Decreasing the cell content decreased the steady response due to a decline in enzymic activity. The treatment of lyophilized cells with ultrasonication or chemically with either N-cetyl-N,N,N-trimethylammonium bromide or guanidine hydrochloride rendered cells permeabilized and exposed the periplasmic enzyme to penicillin. The response time became shorter, but a serious decline in steady responses was observed because of the loss of enzyme activity during the cell permeabilization. The microbial electrode also showed different responses to penicillin G solution, depending on the pH and buffer concentration.

Prevalence of bacterial respiratory pathogens in the nasopharynx in breast-fed versus formula-fed infants.

In several studies, breast-feeding has been associated with decreased frequency or duration of otitis media episodes. If a causal relationship exists, the mechanism of protection of breast-feeding has not been established. We hypothesized that infants who are breast-fed, compared with infants who are formula-fed, have a lower prevalence of nasopharyngeal colonization with the bacterial respiratory pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pyogenes) commonly isolated from the middle ear effusions of children with acute otitis media. In two private pediatric practices, we obtained specimens from the nasopharynx for culture from 211 infants at 1 month of age and from 173 of these infants at 2 months of age. A swab was left in place in the nasopharynx for 45 s and was then immediately transferred onto appropriate culture media. Exclusively breast-fed (n = 84) and exclusively formula-fed (n = 76) infants were similar regarding the number of persons in the household, the number of children in the household, the number of siblings in day care, and the proportion with a recent upper respiratory tract infection. The two groups did not differ significantly in the proportions found to have one or more respiratory pathogens at 1 month of age (10.7 versus 18.4%; P = 0.12) or 2 months of age (34.8 versus 35.1%; P = 0.57). We conclude that during the first 2 months after birth, the exclusive receipt of breast milk appears not to substantially influence the prevalence of nasopharyngeal colonization with common bacterial respiratory pathogens.

Prevalence of urinary tract infection in febrile infants.

Urinary tract infection (UTI), a relatively common cause of fever in infancy, usually consists of pyelonephritis and may cause permanent renal damage. This study assessed (1) the prevalence of UTI in febrile infants (temperature > or = 38.3 degrees C) with differing demographic and clinical characteristics and (2) the usefulness of urinalysis in diagnosing UTI. We diagnosed UTI in 50 (5.3%) of 945 febrile infants if we found > or = 10,000 colony-forming units of a single pathogen per milliliter in a urine specimen obtained by catheterization. Prevalences were similar in (1) infants aged < or = 2 months undergoing examination for sepsis (4.6%), (2) infants aged > 2 months in whom UTI was suspected, usually because no source of fever was apparent (5.9%), and (3) infants with no suspected UTI, most of whom had other illnesses (5.1%). Female and white infants had significantly more UTIs, respectively, than male and black infants. In all, 17% of white female infants with temperature > or = 39 degrees C had UTI, significantly more (p < 0.05) than any other grouping of infants by sex, race, and temperature. Febrile infants with no apparent source of fever were twice as likely to have UTI (7.5%) as those with a possible source of fever such as otitis media (3.5%) (p = 0.02). Only 1 (1.6%) of 62 subjects with an unequivocal source of fever, such as meningitis, had UTI. As indicators of UTI, pyuria and bacteriuria had sensitivities of 54% and 86% and specificities of 96% and 63%, respectively. In infants with fever, clinicians should consider UTI a potential source and consider a urine culture as part of the diagnostic evaluation.

[Serotype distribution of Pseudomonas aeruginosa. Comparative studies of nosocomial and community strains].

A total of 202 strains of Pseudomonas aeruginosa were collected from December 1980 to September 1982 at National Taiwan University Hospital. Of the 202 strains, 102 were nosocomial strains and the other 100 were community strains. The distribution of O antigen group were as follow: E, 34.2%; B, 17.3%; G, 10.9%; F, 9.9%, I, 7.9%; L, 7.4%; others, 12.4%. The antisera used were produced by Toshiba Kagaku Kogyo Co., Japan. The relationship between antibiotic susceptibility pattern and O antigen group were that group-I was the most susceptible group and group-L was the most resistant group. With the O antigen grouping and antibiotic susceptibility pattern, we tried to differentiate the nosocomial strains from the community strains. No obvious difference could be drawn.

Comparison of in vitro antibacterial activity of four oral cephems: cephalexin, cefaclor, cefatrizine and cefadroxil.

The in vitro antibacterial activity of four oral cephems: cephalexin, cefaclor, cefatrizine and cefadroxil against clinical isolates of staphylococci, Enterobacteriaceae and Pseudomonas aeruginosa was compared by agar dilution method. All drugs had comparable antistaphylococcal activity. Cefatrizine and cefaclor were more active than cephalexin and cefadroxil against Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis. All four drugs were relatively inactive against isolates of Enterobacter species and indole-positive Proteus. However, cefatrizine demonstrated the greatest activity of the four oral cephems against these organisms. None of these oral cephems was active against Serratia marcescens or Pseudomonas aeruginosa.