Volumetric assessment of the sella turcica: a re-evaluation.

BACKGROUND: The sella turcica volume is widely measured by the Di Chiro-Nelson method. The purpose is to compare the fidelity of a proposed volumetry method vs. the Di Chiro-Nelson method, using computed tomography (CT) images. MATERIALS AND METHODS: Morphometric examination of 173 CT scans were included, of which 52.6% were female. The mean age was 53.2 ± 17.6 years. Considering the Di Chiro-Nelson method, two measurements were added for each axis in the CT evaluation: length (central, left, and right), width (central, anterior, and posterior), and height (central, left, and right). RESULTS: The mean measurements were length: central 10.11 ± 1.44, left 7.45 ± 1.67, right 7.53 ± 1.59; width: central 12.27 ± 2.11, anterior 10.99 ± 1.92, posterior 10.10 ± 1.74; height: central 7.68 ± 1.38, left 7.16 ± 1.35, right 7.40 ± 1.41. A statistically significant difference between sexes was found only in the anterior width (p = 0.01). Using the proposed method, the volume was 342.2 ± 88.5 and 378. 6 ± 113.9 mm³, respectively for females and males (p = 0.02) vs. 476.1 ± 132.4 and 523.8 ± 186.0 mm3 (p = 0.05) using the Di Chiro-Nelson's method. CONCLUSIONS: Women had significantly smaller sella turcica volume than men. This proposed method considers the sella turcica as a not strictly symmetrical structure and indicates reduced variation between the maximum and minimum values, compared to the Di Chiro-Nelson's. Our findings may be useful for reassessment the volume of the sella turcica as the measurements indicate a higher precision.

Glycine rich segments adopt polyproline II helices: Implications for biomolecular condensate formation.

Many intrinsically disordered proteins contain Gly-rich regions which are generally assumed to be disordered. Such regions often form biomolecular condensates which play essential roles in organizing cellular processes. However, the bases of their formation and stability are still not completely understood. Based on NMR studies of the Gly-rich H. harveyi "snow flea" antifreeze protein, we recently proposed that Gly-rich sequences, such as the third "RGG" region of Fused in Sarcoma (FUS) protein, may adopt polyproline II helices whose association might stabilize condensates. Here, this hypothesis is tested with a polypeptide corresponding to the third RGG region of FUS. NMR spectroscopy and molecular dynamics simulations suggest that significant populations of polyproline II helix are present. These findings are corroborated in a model peptide Ac-RGGYGGRGGWGGRGGY-NH2, where a peak characteristic of polyproline II helix is observed using CD spectroscopy. Its intensity suggests a polyproline II population of 40%. This result is supported by data from FTIR and NMR spectroscopies. In the latter, NOE correlations are observed between the Tyr and Arg, and Arg and Trp side chain hydrogens, confirming that side chains spaced three residues apart are close in space. Taken together, the data are consistent with a polyproline II helix, which is bent to optimize interactions between guanidinium and aromatic moieties, in equilibrium with a statistical coil ensemble. These results lend credence to the hypothesis that Gly-rich segments of disordered proteins may form polyproline II helices which help stabilize biomolecular condensates.

Morphometry of the aortic arch and its branches. A computed tomography angiography-based study.

BACKGROUND: The current study aims to determine the prevalence of variations of the aortic arch using computed tomography angiography (CTA), as well as morphometries and gender correlations. MATERIALS AND METHODS: A retrospective, transverse, observational and descriptive study of 220 CTA was performed. The branching pattern, most cranial vertebral level of the aortic arch, area of the proximal, middle and distal segments of the arch, area of each branch, and the path of atypical arteries were recorded. Results were analysed and stratified by gender. RESULTS: The typical aortic arch branching pattern was present in 77.7% without statistical significance between genders. The most common variant was a two-branch pattern with a common trunk and a left subclavian (13.6%), followed by a typical branching pattern with an added left vertebral artery (7.3%). T3 was the most frequent cranial level (32.3%), followed by T2-T3 (26.8%), and T3-T4 (23.2%). The mean areas of the aortic arch were 685.5 ± 183.9, 476.1 ± 124.1, and 445.0 ± 145.1 mm2 for the proximal, middle and distal segments, with statistical difference between men and women in the middle and distal segments. Three paths of atypical arteries were identified: bifurcated vertebral artery (0.5%), aberrant right subclavian artery (0.5%), and left subclavian ostium obstruction (0.5%). CONCLUSIONS: Mexican population has one of the highest prevalence of variations in the aortic arch branching pattern. The high probability of finding these should be taken into consideration when assessing patients. A standardised classification method would contemplate future un-reported findings, without causing confusion by the different numbers assigned by each author.

Sex-related differences in muscle size explained by amplitudes of higher-threshold motor unit action potentials and muscle fibre typing.

AIM: To investigate the relationships between motor unit action potential amplitudes (MUAPAMP ), muscle cross-sectional area (mCSA) and composition (mEI), per cent myosin heavy chain (%MHC) areas and sex in the vastus lateralis (VL). METHODS: Ten males and 10 females performed a submaximal isometric trapezoid muscle action that included a linearly increasing, steady torque at 40% maximal voluntary contraction, and linearly decreasing segments. Surface electromyographic decomposition techniques were utilized to determine MUAPAMPS in relation to recruitment thresholds (RT). Ultrasound images were taken to quantify muscle mCSA and mEI. Muscle biopsies were collected to calculate %MHC areas. Y-intercepts and slopes were calculated for the MUAPAMP vs RT relationships for each subject. Independent-samples t tests and ANOVA models examined sex-related differences in mCSA, mEI, slopes and y-intercepts for the MUAPAMP vs RT relationships and %MHC areas. Correlations were performed among type IIA and total type II %MHC area, mCSA and the slopes and y-intercepts for the MUAPAMP vs RT relationships. RESULTS: Males exhibited greater slopes for the MUAPAMP vs RT relationships (P = .003), mCSA (P < .001) and type IIA %MHC (P = .011), whereas females had greater type I %MHC area (P = .010) and mEI (P = .024). The mCSA, type IIA and total II %MHC area variables were correlated (P < .001-.015, r = .596-.836) with the slopes from the MUAPAMP vs RT relationships. CONCLUSION: Sex-related differences in mCSA and MUAPAMPS of the higher-threshold MUs were likely the result of larger muscle fibres expressing type II characteristics for males.

The change in motor unit firing rates at de-recruitment relative to recruitment is correlated with type I myosin heavy chain isoform content of the vastus lateralis in vivo.

AIM: To investigate the change in motor unit (MU) firing rates (FR) at de-recruitment relative to recruitment and the relation to % type I myosin heavy chain isoform content (type I %MHC) of the vastus lateralis (VL) in vivo. METHODS: Ten subjects performed a 22-s submaximal isometric trapezoid muscle action that included a linearly increasing, steady force at 50% maximal voluntary contraction, and linearly decreasing segments. Surface electromyographic signals were collected from the VL and were decomposed into constituent MU action potentials trains. A tissue sample from the VL was taken to calculate type I %MHC. The y-intercepts and slopes were calculated for the changes (Δ) in FR at de-recruitment (FRDEREC ) relative to FR at recruitment (FRREC ) vs. FRREC relationship for each subject. Correlations were performed between the y-intercepts and slopes with type I %MHC. RESULTS: The majority of MUs had greater FRDEREC than FRREC . The y-intercepts (r = -0.600, P = 0.067) were not significantly correlated, but the slopes (r = -0.793, P = 0.006) were significantly correlated with type I %MHC. CONCLUSION: The majority of the motoneuron pool had greater FRDEREC than FRREC , however, individuals with higher type I %MHC had a greater propensity to have MUs with FRREC > FRDEREC as indicated by the slope values. Overall, the contractile properties of the muscle (MHC) could partially explain the differences in MU firing rates at de-recruitment relative to recruitment. Thus, suggesting the fatigability of the muscle influences the alterations in MU firing rates from recruitment to de-recruitment.

HLA-target antigens and T-cell receptor diversity of activated T cells invading the skin during acute graft-versus-host disease.

To study the repertoire and specificity of T lymphocytes infiltrating skin lesions during graft-versus-host disease (GVHD), we performed an exhaustive molecular and functional analysis of 146 T-cell clones derived from the skin of three patients undergoing an acute GVHD after allogeneic bone marrow transplantation (BMT) from HLA-mismatched related donors. Analysis of T-cell receptor (TCR) rearrangement and TCR chain junctional sequences demonstrated the presence of 11 distinct clones among the 64 derived from patient UPN1, six among the 58 derived from patient UPN2, and seven among the 24 derived from patient UPN3. Three of the 11 T-cell clones from patient UPN1, and all clones from patients UPN2 and UPN3 reacted with mismatched HLA alleles between the bone-marrow donor and recipient. Moreover, both HLA class I (HLA-A2 and -B27) and class II (HLA DP101, DP401, DP1301, DQ8, and DR402) molecules were recognized during this early antihost response. Finally, both TCR alpha and beta chains turned out to be extremely diverse, even within populations of clones derived from the same patient and directed against the same HLA allele. Taken together, these results indicate that any HLA mismatch is potentially targeted during early GVHD, and that the T-cell response at the onset of GVHD is both oligoclonal and highly diversified.

Allelic polymorphism in the coding region of human TCR C alpha gene and characterization of structural variability in the alpha chain constant domain.

An allelic variant of the human TCR C alpha gene, designated C alpha AL, which encodes a structurally different protein product has been characterized. C alpha AL was independently sequenced using polymerase chain reaction (PCR)-amplified TCR C alpha cDNA from various T cell clones derived from a same individual. It differed from the most usual C alpha sequence by two non-synonymous base changes at codons 4 (AAC-->AAG) and 84 (GAA-->GCA) of the C alpha coding region. These changes imply amino acid substitutions Asn-->Lys and Glu-->Ala respectively. An oligotyping method, based on hybridization of allele-specific oligonucleotides to PCR-amplified C alpha DNA, is also described. It was used for differential typing of the two C alpha forms in family and population studies. In each of three T cell clones analyzed from the same donor having two rearranged TCR alpha chain transcripts, C alpha AL was found in only one of the transcripts. In addition, C alpha AL segregated as a co-dominant mendelian allele within the family of this donor. Population analysis was carried out in 73 spanish individuals. Twelve donors (16.4%) were heterozygous, implying that C alpha AL was present in this population sample with an allelic frequency of 0.08. The observed frequencies of C alpha genotypes were those expected for the two alleles being in Hardy-Weinberg equilibrium. This demonstration of structural polymorphism in the constant region of TCR alpha chains provides a useful genetic marker for TCR and disease association studies due to its precise mapping within the C alpha coding region, and its significant frequency in the analyzed population.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of severe hydrofluoric acid exposures.

Previous publications on treatment of hydrofluoric acid exposures have given insufficient emphasis to immediate skin cleansing and prompt restitution of both serum and tissue calcium ion levels. Use of calcium gluconate topically as a 2.5% gel, in eyes as a 1% solution, and by nebulizer as a 2.5% or 3% solution has improved treatment results. Ten percent calcium gluconate solution may be given intravenously as indicated for hypocalcemia. Proper application of the calcium gluconate gel immediately after thorough washing of localized skin burns will produce relief of pain similar to that achieved by subcutaneous infiltration of 5% calcium gluconate solution. This may be used as an end-point for adequacy of treatment.