Gastric tonometry in septic shock

OBJECTIVES: To investigate the prognostic value of intramucosal pH (pHi) and the relation among pHi, arterial pH, base excess, and lactate in children with septic shock. DESIGN: Children admitted to the paediatric intensive care unit with a diagnosis of septic shock were prospectively enrolled. A gastrointestinal tonometer (Tonometrics Division, Instrumentarium Corporation, Helsinki, Finland) was placed into the stomach and intramucosal pH, arterial pH, base deficit, and lactate were measured on admission and six hours later. Sequential data were analysed on 24 patients (17 survivors, seven non-survivors), median age 46 months (range: 2.8-168 months). RESULTS: Median pHi on admission was 7.39 (interquartile range 7.36-7.51) in survivors compared with 7.2 (interquartile range 7.18-7.35) in non-survivors (p = 0.01). There was no significant difference in arterial pH, base excess, or lactate among survivors and non-survivors. Admission pHi < 7.32 predicted mortality with sensitivity (57%), specificity (94%), and positive predictive value (80%). Patients with admission pHi < 7.32 who failed to improve > or = 7.32 within six hours (n = 3) had 100% mortality. CONCLUSION: In children with septic shock the admission pHi is significantly lower in non-survivors. pHi is a better prognostic indicator of mortality than either standard acid-base values or lactate. pHi < 7.32 that does not improve within six hours is associated with a poor prognosis.     

Tightly linked polymorphic markers for fragile X syndrome and prenatal cytogenetic diagnostic experience

Linkage analysis using the polymorphic loci DXS369, DXS296, DXS297 and DXS306 was carried out on a cohort of 17 families segregating for fragile X syndrome. The observed recombination fractions at: DXS369 (Zmax = 3. 02; theta=0. 06), DXS297 (Zmax= 2. 92; theta = 0.0), DXS296 (Zmax = 3. 82; theta = 0.0), DXA306 (Zmax = 4. 55; theta = 0.05) confirm that these loci are tightly linked to FRAXA. Our experience in the cytogenetic analysis of 58 at risk pregnancies by chorionic villus or fetal blood sample examination documents a false negative rate in obligate carrier male pregnancies for CVS of 11% and for FBS of 3%.     

Transmission of haplotypes of microsatellite markers rather than single marker alleles in the mapping of a putative type 1 diabetes susceptibility gene (IDDM6)

Allelic association methods based on increased transmission of marker alleles will have to be employed for the mapping of complex disease susceptibility genes. However, because the extent of association of single marker alleles with disease is a function of the relative frequency of the allele on disease-associated chromosomes versus non disease-predisposing chromosomes, the most associated marker allele in a region will not necessarily be closest to the disease locus. To overcome this problem we describe a haplotype-based approach developed for mapping of the putative type 1 diabetes susceptibility gene IDDM6. Ten microsatellite markers spanning a 550 kb segment of chromosome 18q21 in the putative IDDM6 region were genotyped in 1708 type 1 diabetic Caucasian families from seven countries. The most likely ancestral diabetogenic chromosome was reconstructed in a stepwise fashion by analysing linkage disequilibrium between a previously defined haplotype of three adjacent markers and the next marker along the chromosome. A plot of transmission from heterozygous parents to affected offspring of single marker alleles present on the ancestral chromosome versus the physical distance between them, was compared with a plot of transmission of haplotypes of groups of three adjacent markers. Analysing transmission of haplotypes largely negated apparent decreases in transmission of single marker alleles. Peak support for association of the D18S487 region with IDDM6 is P = 0.0002 (corrected P = 0.01). The results also demonstrate the utility of polymorphic microsatellite markers to trace and delineate extended and presumably ancient haplotypes in the analysis of common disease and in the search for identical-by-descent chromosome regions that carry an aetiological variant.      

Functional analysis of six androgen receptor mutations identified in patients with partial androgen insensitivity syndrome

Partial androgen insensitivity syndrome (PAIS) is caused by defects in the androgen receptor gene and presents with a wide range of undervirilization phenotypes. We studied the consequences of six androgen receptor ligand-binding domain mutations on receptor function in transfected cells. The mutations, Met742Ile, Met780Ile, Gln798Glu, Arg840Cys, Arg855His and Ile869Met, were identified in PAIS patients with phenotypes representing the full spectrum seen in this condition. In all cases the androgen receptor was found to be defective, suggesting that the mutation is the cause of the clinical phenotype. The Gln798Glu mutation is exceptional in that it did not cause an androgen-binding defect in our system, although the mutant receptor was defective in transactivation assays. This mutation may affect an aspect of binding not tested, or may be part of a functional subdomain of the ligand-binding domain involved in transactivation. Overall we found milder mutations to be associated with milder clinical phenotypes. There is also clear evidence that phenotype is not solely dependent on androgen receptor function. Some of the mutant receptors were able to respond to high doses of androgen in vitro, suggesting that patients carrying these mutations may be the best candidates for androgen therapy. One such mutation is Ile869Met. A patient carrying this mutation has virilized spontaneously at puberty, so in vivo evidence agrees with the experimental result. Thus a more complete understanding of the functional consequences of androgen receptor mutations may provide a more rational basis for gender assignment in PAIS.      

Tyrosine phosphorylation of a 95 kDa protein and induction of the acrosome reaction in human spermatozoa by recombinant human zona pellucida glycoprotein 3

Protein tyrosine phosphorylation and induction of the acrosome reaction (AR) in non-capacitated and capacitated human spermatozoa was investigated in response to recombinant human zona pellucida glycoprotein (rhZP3) produced by Chinese hamster ovary cells transfected with a plasmid containing human ZP3 cDNA. rhZP3-containing medium promoted the AR in a high proportion of capacitated spermatozoa (48.6 +/- 3.2%; P < 0.01) compared with control (no rhZP3) samples (14.8 +/- 2.1%). However, rhZP3-containing medium did not cause increased acrosomal exocytosis in non-capacitated spermatozoa (16.8 +/- 3.0%). Induction of the AR was associated with increased tyrosine phosphorylation of a 95 +/- 5 kDa epitope only in capacitated spermatozoa. A dose-dependent increase in the protein phosphorylation of a 95 kDa epitope in response to rhZP3 was detected by [gamma-32P]- ATP labelling of detergent-solubilized sperm proteins. When spermatozoa were co-incubated with monoclonal antibody 97.25 (mAb 97.25) recognizing a 95 kDa tyrosine kinase epitope, there was no rhZP3 induction of tyrosine phosphorylation of the 95 kDa protein. Such co- incubation also markedly inhibited the AR (23.9 +/- 3.1%). These results support the model that initial interaction of the fertilizing spermatozoon with ZP3 involves the tyrosine phosphorylation of a 95 kDa tyrosine kinase protein and that this requires capacitation.