Transmission of Pneumocystis carinii DNA from a patient with P. carinii pneumonia to immunocompetent contact health care workers

The transmission of Pneumocystis carinii from person to person was studied by detecting P. carinii-specific DNA in prospectively obtained noninvasive deep-nasal-swab samples from a child with a documented P. carinii pneumonia (PCP), his mother, two contact health care workers, and 30 hospital staff members who did not enter the patient's room (controls). Nested-DNA amplification was done by using oligonucleotide primers designed for the gene encoding the mitochondrial large subunit rRNA of rat P. carinii (P. carinii f. sp. carinii) that amplifies all forms of P. carinii and internal primers specific for human P. carinii (f. sp. hominis). P. carinii f. sp. hominis DNA was detected in samples from the patient and all of his contacts versus none of the 30 hospital staff members. The results, as previously shown in murine models of P. carinii pneumonia, document that person-to-person transmission of P. carinii is possible. This observation suggests that immunocompromised patients not on PCP prophylaxis should not enter the room of a patient with PCP, and it also raises the question as to whether healthy contacts can transmit the disease to immunocompromised patients at risk.     

Effect of Gardenia extract ZG on the adsorption quantity of herpes simplex virus type 1 （HSV-1）

To observe the effect of Gardenia extract ZG on the adsorption quantity of herpes simplex virus type 1 (HSV-1) so as to explore the mechanism of its antiviral activity, fluorescein isothiocyanate (FITC) was used as the fluorescent probe to label viruses and heparin sodium was used as control. Meanwhile , the effect of Gardenia extract ZG on the adsorption quantity on the surface of Hep-2 cells was determined by flow cytometry. It was demonstrated that adsorption of HSV-1 on the surface of Hep-2 cells exhibited the character of saturation and specificity and heparin sodium could prevent attachment of viruses on these cells. These results are in accord with those reported previously. It was also proved that the manner of drug-use prior to adsorption or simultaneous use of drug and adsorption was better than adsorption prior to drug-use, and the inhibition rates of the former and latter manner were 84. 76% and 82.92% respectively. Three manners of drug-use with Gardenia extract ZG were all effective to reduce the adsorption quantity of viruses, especially the manner of simultaneous use of drug and adsorption with an adsorption inhibition rate of 68.46% . From the above observation, it is apparent that the mechanism of anti-viral activity of Gardenia extract ZG may be via several steps involved in the HSV-1 adsorption.     

Evaluation of a new enzyme immunoassay for Clostridium difficile toxin A.

AIM: To evaluate a new enzyme immunoassay (EIA) method for detection of Clostridium difficile toxin by comparing it to cytotoxicity assay. To investigate the nature of false negative and false positive EIA results by evaluating clinical and therapeutic parameters. METHODS: 737 consecutive diarrhoeal specimens collected from patients clinically suspected of having C difficile colitis were tested for the presence of C difficile toxin by EIA for toxin A and by cytotoxicity assay. Clinical data were evaluated in all cases positive by either method. RESULTS: With the cytotoxicity assay as a gold standard, the specificity of EIA for toxin detection was 99.3% and the sensitivity was 62.2%. No false negative EIA specimens were obtained from patients already being treated for C difficile colitis. Among patients with cytotoxicity positive specimens, those with EIA positive samples had no clinical features distinguishing them from patients with EIA negative samples. CONCLUSIONS: Although specific, the new EIA method directed against toxin A lacks sensitivity compared to cytotoxicity. False negative EIA tests are not associated with concurrent treatment for C difficile colitis nor with any specific clinical features examined in our study.     

耳大神经及腮腺筋膜解剖的再认识与腮腺切除手术的改良

目的：对耳大神经及腮腺筋膜解剖进行再认识，由此改良腮腺切除手术方法。方法：解剖成人尸体10侧，术中活体解剖20侧，对耳大神经和腮腺筋膜的解剖要素进行观察。根据观察结果进行改良腮腺切除术14例，即在腮腺筋膜表面翻瓣后，由前向后另翻腮腺筋膜瓣，切除腮腺后将筋膜瓣复位缝合，完整保留耳大神经和腮腺筋膜。结果：耳大神经在下颌角水平之上0-2cm依次分耳后、耳垂、耳前支，神经主干末段和分支起始段均分布于腮腺筋膜浅层表面，后者致密，其致密纤维包裹在神经周围。改良手术后2例（14．3％）发生轻度Frey’s综合征，无1例发生术区皮肤长期麻木、长期面瘫、涎瘘及肿瘤复发。结论：耳大神经各分支和腮腺筋膜具有不可代替的解剖生理功能，改良术式能将两者完好保留，显著降低术后并发症。     

The interface between tapasin and MHC class I: identification of amino acid residues in both proteins that influence their interaction

Prior to the binding of antigenic peptide, a complex of chaperone proteins associates with the Major Histocompatibility Complex (MHC) class I heavy chain/β₂m heterodimer. Although each dornain of the MHC class I heavy chain contains amino acid resid uses that influence chaperone binding, there are several pieces of evidence that point to an interaction between the MHC clas 1α2/α3 domains and tapasin. In egard to the site on tapasin involved in the tapasin/MHC interface, we have found that a particular region of tapasin (containing amino acid residues 334–342) is necessary for the binding of tapasin to the MHC class I heavy chain. Our results also indicate that amino acids in this region of tapasin also affect the proportion of MHC class I open forms expressed at the cell surface and MHC class I egress from the endoplasmic reticulurn. Based on these results and those obtained by other laboratories, a model for MHC class I/tapasin interaction is proposed.     

Gamma delta lymphocytes in endocrine autoimmunity: evidence of expansion in Graves' disease but not in type 1 diabetes.

Endocrine autoimmune disorders are mediated by T cell-dependent responses to organ-specific antigens, but the mechanisms initiating the process remain unknown. Lymphocytes which use the gamma delta heterodimer as T cell receptor (TCR) for antigen constitute a distinct subset of T cells whose function remains elusive. In order to investigate their possible involvement in endocrine autoimmunity we have determined the proportion of gamma delta T cells in the peripheral blood of 23 patients with type 1 (insulin-dependent) diabetes mellitus (type-1 DM) and 30 patients with autoimmune thyrotoxicosis (Graves' disease). T lymphocyte TCR expression was assessed by fluorescence-activated flow cytometry on peripheral blood mononuclear cells using MoAbs UCHT1 (CD3), TCR delta 1 (gamma delta TCR), WT31 and beta F1 (alpha beta TCR) and both the percentage of T cells expressing gamma delta and the ratio gamma delta/alpha beta were calculated. In the diabetic patients gamma delta cells were not significantly different from the control group (7.7 +/- 54% versus 8.0 +/- 5.5% of T cells, P NS). There was no relation between the proportion of gamma delta lymphocytes and the presence of islet cell antibodies (ICA) in the sera. The Graves' patients showed a tendency towards a higher proportion of gamma delta T lymphocytes than the controls (gamma delta/alpha beta ratios: 0.095 +/- 0.047 versus 0.063 +/- 0.022, P = 0.03). In 14 Graves' patients the number of gamma delta were measured in paired samples of peripheral and intrathyroidal lymphocytes, demonstrating an expansion of gamma delta within the thyroid glands (0.21 +/- 0.3 versus 0.095 +/- 0.047, P = 0.032). Immunohistochemical studies showed that gamma delta cells were scattered among the predominant alpha beta lymphocytes infiltrating the thyroid gland and that they account for 10% of intraepithelial lymphocytes. No relation was found between the increase of gamma delta lymphocytes and any clinical features.     

Identification of three novel RB1 mutations in Brazilian patients with retinoblastoma by "exon by exon" PCR mediated SSCP analysis

AIMS: To carry out a retrospective study, screening for mutations of the entire coding region of RB1 and adjacent intronic regions in patients with retinoblastoma. METHODS: Mutation screening in DNA extracts of formalin fixed, paraffin wax embedded tissues of 28 patients using combined "exon by exon" polymerase chain reaction mediated single strand conformational polymorphism analysis, followed by DNA sequencing. RESULTS: Eleven mutations were found in 10 patients. Ten mutations consisted of single base substitutions; 10 were localised in exonic regions (eight nonsense, one missense, and one frameshift) and another one in the intron-exon splicing region. Three novel mutations were identified: a 2 bp insertion in exon 2 (g.5506-5507insAG, R73fsX77), a G to A transition affecting the last invariant nucleotide of intron 13 (g.76429G>A), and a T to C transition in exon 20 (g.156795T>C, L688P). In addition, eight C to T transitions, resulting in stop codons, were found in five different CGA codons (g.64348C>T, g.76430C>T, g.78238C>T, g.78250C>T, and g.150037C>T). Although specific mutation hotspots have not been identified in the literature, eight of the 11 mutations occurred in CGA codons and seven fell within the E1A binding domains (codons 393-572 and 646-772), whereas five were of both types-in CGA codons within E1A binding domains. CONCLUSIONS: CGA codons and E1A binding domains are apparently more frequent mutational targets and should be initially screened in patients with retinoblastoma. Paraffin wax embedded samples proved to be valuable sources of DNA for retrospective studies, providing useful information for genetic counselling.     

Classroom aeroallergen exposure in Arkansas head start centers.

BACKGROUND: The impact of preschool environmental conditions on classroom aeroallergen concentrations is not fully understood. OBJECTIVE: To examine the relationship between school environmental conditions and classroom aeroallergen concentrations in the Pulaski County Head Start (HS) Program. METHODS: Thirty-three HS centers in Pulaski County, Arkansas, underwent a detailed environmental evaluation. Classroom settled dust samples were analyzed for the presence of common indoor allergens. RESULTS: Classroom eating (70%), wall-to-wall carpeting (58%), and water damage (33%) were common. Median classroom allergen levels were as follows: dust mite (Der p 1 and Der f 1), 0.6 microg/g; Fel d 1, 0.4 microg/g; Can f 1, 1.7 microg/g; cockroach, below detection; Mus m 1, 0.18 microg/g; and mold spores, 17,800 CFU/g. Can f 1 and Mus m 1 allergens were detected in 100% of HS centers. Facilities with carpeting, increased humidity, and single-use facilities showed trends toward increased dust mite concentrations. Detectable cockroach allergen was more common in classrooms cleaned by teachers than by professional housekeepers. CONCLUSIONS: Aeroallergens were commonly detected in Pulaski County HS center classrooms, with dog and mouse allergens detected in 100% of centers. Median classroom allergen concentrations were low, and classroom characteristics were not strongly predictive of increased allergen exposure.