Measurement of the normal optic chiasm on coronal MR images.

PURPOSETo develop an objective method for measuring the optic chiasm and to document its normal range in size.METHODSMeasurements of the height and area of the optic chiasm, made on coronal T1-weighted MR images with the use of commercially available region-of-interest software, were obtained in 114 healthy subjects who had a total of 123 MR studies. A normal range and standard deviation were calculated, and the information was broken down by age and sex.RESULTSThe mean area of the optic chiasm was 43.7 mm2, with a standard deviation of 5.21. The mean width was 14.0 mm, with a standard deviation of 1.68.CONCLUSIONThe area and width of the optic chiasm can be measured with the use of commercially available software, which allows an objective estimate of the chiasm''s size. Knowledge of the normal size range of the optic chiasm can be helpful in the early detection of some disorders.     

Proliferative and cytolytic responses of human gamma delta T cells display a distinct specificity pattern.

The function and physiological role of gamma delta T cells are still unknown. Concerning the specificity of these cells, a proliferative response towards microbial ligands has been noted, whereas in terms of effector functions in humans a cytolytic activity against a variety of tumour targets is most prominent. Here we show data demonstrating that the cytolytic activity of activated human gamma delta T cells does not reflect the specificity of these cells in primary in vitro stimulation; moreover, we provide evidence that the recognition of target cells by gamma delta T cells can have different qualities. gamma delta T cells proliferate vigorously in primary in vitro reaction upon stimulation with various B-cell tumour lines but not with the T-cell lines Jurkat or Molt-4. However, gamma delta T cells stimulated primarily with phytohaemagglutinin or with cells from B-cell lines gain unrestricted cytolytic activity against a broad set of tumour targets, including Jurkat and Molt-4; the same set of targets is capable of inducing release of serine esterases (SE) from gamma delta T-effector cells. Whereas the cytolytic activity in the 51Cr-assay against the B-cell lines and against Molt-4 depends on the presence of Ca2+ ions in the assay, the lysis of Jurkat cells is only slightly reduced upon removal of Ca2+ from the medium; the SE release, however, is Ca2+ dependent in all cases. Taken together, these data suggest several different ways of target cell recognition by gamma delta T cells leading to either proliferation or triggering of cytolytic activity, and argue against an involvement of the gamma delta T-cell receptor in the cytotoxic activity of gamma delta T cells.     

Molecular analysis and polymorphism of the DLA-DQB genes

Abstract: Partial-length cDNA clones and full-length genomic clones corresponding to a complete canine DQB class It gene were isolated. Southern analyses suggested the presence of two DQB genes - one of which appeared to be a pseudogene lacking exon 2 called DQB2. The other DQB gene, called DQB1, was isolated from a genomic phage clone and contained six exons. The DQB1 clone was restriction mapped, and exon 2 was sequenced from 70 dogs. Twenty alleles were found. Most of the amino acid substitutions occurred at putative positions in the peptide binding site. Inheritance of these sequences showed Mendelian segregation with one or two alleles per dog. Cluster analysis of the nucleotide and predicted amino acid sequences subdivided the canine DQB1 alleles into four major allelic groups. The number of nonsynonymous changes was higher than the number of synonymous changes in the putative antigen recognition sites suggestive of positive selection.     

Lack of Nonshivering Thermogenesis in Infants Anesthetized with Fentanyl and Propofol

Background: Sweating, vasoconstriction, and shivering have been observed during general anesthesia. Among these, vasoconstriction is especially important because-once triggered-it minimizes further hypothermia. Surprisingly, the core-temperature plateau associated with vasoconstriction appears to preserve core temperature better in infants and children than adults. This observation suggests that vasoconstriction in anesthetized infants may be accompanied by hypermetabolism. Consistent with this theory, unanesthetized infants rely on nonshivering thermogenesis to double heat production when vasoconstriction alone is insufficient. Accordingly, the authors tested the hypothesis that intraoperative core hypothermia triggers nonshivering thermogenesis in infants.

Methods: With Ethics Committee approval and written parental consent, the authors studied six infants undergoing abdominal surgery. All were aged 1 day to 9 months and weighed 2.4-9 kg. Anesthesia was maintained with propofol and fentanyl. The infants were mechanically ventilated and allowed to cool passively until core (distal esophageal) temperatures reached 34-34.5 degrees Celsius. Oxygen consumption-the authors' index of metabolic rate- was recorded throughout cooling. Because nonshivering thermogenesis triples circulating norepinephrine concentrations, arterial blood was analyzed for plasma catecholamines at [nearly equal] 0.5 degrees Celsius intervals. Thermoregulatory vasoconstriction was evaluated using forearm - fingertip, skin-surface gradients, with gradients exceeding 4 degrees Celsius, indicating intense vasoconstriction. The patients were subsequently rapidly rewarmed to 37 degrees Celsius. Regression analysis was used to correlate changes in oxygen consumption and plasma catecholamine concentrations with core temperature.

Results: All patients were vasoconstricted by the time core temperature reached 36 degrees Celsius. Further reduction in core temperature to 34-34.5 degrees Celsius did not increase oxygen consumption. Instead, oxygen consumption decreased linearly. Hypothermia also failed to increase plasma catecholamine concentrations.     

Rh phenotype prediction by DNA typing and its application to practice

The complexity of the RHD and RHCE genes, which is the greatest of all blood group systems, confounds analysis at the molecular level. RH DNA typing was introduced in 1993 and has been applied to prenatal testing. PCR-SSP analysis covering multiple polymorphisms was recently introduced for the screening and initial characterization of partial D. Our objective is to summarize the accrued knowledge relevant to the approaches to Rh phenotype prediction by DNA typing, their possible applications beyond research laboratories and their limitations. The procedures, results and problems encountered are highly detailed. It is recommended that DNA typing comprises an analysis of more than one polymorphism. We discuss future directions and propose a piecemeal approach to improve reliability and cost-efficiency of blood group genotyping that may eventually replace the prevalent serology-based techniques even for many routine tasks. Transfusion medicine is in the unique position of being able to utilize the most extensive phenotype databases available to check and develop genotyping strategies.     

Microalbuminuria in children and adolescents with and without Type-I diabetes mellitus (IDDM)

In 73 healthy (group I) and 32 children and juveniles with insulin dependent diabetes mellitus (IDDM, group II) urinary albumin excretion is determined by radioimmunoassay (RIA). In both groups albumin excretion is observed in every urine sample when measured by RIA (mean +/- SD: group I: 7-19 h: 5.17 +/- 5.28 mg, 19-7 h: 3.86 +/- 4.00 mg, 24 h: 9.03 +/- 8.60 mg; group II: 7-19 h: 6.68 +/- 6.86 mg, 19-7 h: 3.46 +/- 2.82 mg, 24 h: 10.13 +/- 9.25 mg). No significant difference is detected between the values of the two groups. However in diabetic patients a significant difference is observed between diurnal and nocturnal urinary albumin excretion. Microalbuminuria is defined as an albumin excretion above 30 mg/d and is present in 6.9% of the values in group I and in 3.1% in group II. The physiological limits of microalbuminuria in children and juveniles compared to adults and several methods of urine sampling are discussed.     

Sensitivity and specificity of screening for Down syndrome with alpha-fetoprotein, hCG, unconjugated estriol, and maternal age.

The sensitivity and specificity of maternal serum screening for Down syndrome with different biochemical markers were evaluated. Detection rates with different combinations of maternal serum alpha-fetoprotein (MSAFP), hCG, and unconjugated estriol (uE3) were established by retrieving and analyzing 54 serum specimens from women with confirmed Down syndrome pregnancies, compared with 657 specimens from women with normal outcomes. With a risk cutoff of 1:270 at the second trimester, the detection rate with MSAFP, hCG, and uE3 was two to three times higher than with MSAFP alone. With all three markers, the detection rate for Down syndrome increased from 50 to 77% as maternal age increased, and was 60% in a representative screened population. If uE3 was omitted, the detection rate decreased from 60 to 48%. One thousand women were screened prospectively, either with MSAFP or with all three markers prospectively, either with MSAFP or with all three markers and 4.1% with MSAFP. With the three markers, the positive predictive value for Down syndrome was 2.2% overall and as high as 5.9% in older women. Therefore, the addition of hCG and uE3 to the maternal serum screen increases the positive predictive value by 50-300%, depending on maternal age. These results confirm the efficacy of screening for Down syndrome using maternal age and three serum markers.     

Decreased sensitivity to experimental pain in adjustment disorder.

An altered perception of pain has been described for several psychiatric disorders. To date the influence of adjustment disorders (AD) on pain perception has not been described. Here, we investigated perception of experimentally induced pain in 15 patients suffering from AD (subtype with depressive symptoms) and controls matched for age and sex. Thresholds and tolerances were assessed for thermal and electrical pain on both sides of the body. We found an overall increase of pain thresholds and tolerances in AD patients as compared to controls, predominately on the right side of the body. Analogue findings have been reported for pain perception in major depressive disorder (MDD). Of the data obtained, only thermal pain threshold on the right arm correlated with the severity of depressive symptoms. Although the underlying pathology is elusive it is likely that the mechanisms for reduced pain sensitivity are comparable in MDD and AD.