Oxygen Therapy for Spontaneous Pneumothorax

The rate of absorption of gas from a pneumothorax was studied in 12 patients breathing air and in 10 patients breathing air and a high concentration of oxygen alternately. The mean rate of absorption while breathing air was the same in both groups of patients. In the second group the rate consistently increased during periods of oxygen therapy and decreased again on breathing air. The mean rate of absorption increased fourfold during periods of oxygen therapy. This increase was most pronounced in patients with a large pneumothorax.     

Recurrent Haemorrhage after Acute Gastrointestinal Bleeding

A retrospective survey of 472 consecutive hospital admissions for acute upper gastrointestinal bleeding showed that patients with a large initial bleed are more likely to bleed again than those with a small initial bleed. The incidence of recurrent haemorrhage is also related to the interval since the last bleeding episode, so that patients showing no clinical evidence of haemorrhage for 48 hours are unlikely to bleed again in the near future. Patients admitted after a haematemesis have a higher incidence of recurrent haemorrhage than those admitted after melaena only. Aetiology has been confirmed as an additional important factor, the incidence being highest in those with oesophageal varices or a chronic gastric ulcer. Contrary to widespread belief, age does not appear to affect the incidence of recurrent haemorrhage, nor do other constitutional factors such as sex or the ABO blood group.     

Contractile behavior of the forelimb digital flexors during steady-state locomotion in horses (Equus caballus): an initial test of muscle architectural hypotheses about in vivo function

The forelimb digital flexors of the horse display remarkable diversity in muscle architecture despite each muscle-tendon unit having a similar mechanical advantage across the fetlock joint. We focus on two distinct muscles of the digital flexor system: short compartment deep digital flexor (DDF(sc)) and the superficial digital flexor (SDF). The objectives were to investigate force-length behavior and work performance of these two muscles in vivo during locomotion, and to determine how muscle architecture contributes to in vivo function in this system. We directly recorded muscle force (via tendon strain gauges) and muscle fascicle length (via sonomicrometry crystals) as horses walked (1.7 m s(-1)), trotted (4.1 m s(-1)) and cantered (7.0 m s(-1)) on a motorized treadmill. Over the range of gaits and speeds, DDF(sc) fascicles shortened while producing relatively low force, generating modest positive net work. In contrast, SDF fascicles initially shortened, then lengthened while producing high force, resulting in substantial negative net work. These findings suggest the long fibered, unipennate DDF(sc) supplements mechanical work during running, whereas the short fibered, multipennate SDF is specialized for economical high force and enhanced elastic energy storage. Apparent in vivo functions match well with the distinct architectural features of each muscle.     

Large scale analysis of pediatric antiviral CD8+ T cell populations reveals sustained, functional and mature responses

Background

Cellular immunity plays a crucial role in cytomegalovirus (CMV) infection and substantial populations of CMV-specific T cells accumulate throughout life. However, although CMV infection occurs during childhood, relatively little is know about the typical quantity and quality of T cell responses in pediatric populations.

Methods

One thousand and thirty-six people (Male/Female = 594/442, Age: 0–19 yr.; 959 subjects, 20–29 yr.; 77 subjects) were examined for HLA typing. All of 1036 subjects were tested for HLA-A2 antigen. Of 1036 subjects, 887 were also tested for HLA-A23, 24 antigens. In addition, 50 elderly people (Male/Female = 11/39, Age: 60–92 yr.) were also tested for HLA-A2 antigen. We analyzed the CD8+ T cell responses to CMV, comparing these to responses in children and young. The frequencies, phenotype and function CD8+ T cells for two imunodominant epitopes from pp65 were measured.

Results

We observed consistently high frequency and phenotypically "mature" (CD27 low, CD28 low, CD45RA+) CMV-specific CD8+ T cell responses in children, including those studied in the first year of life. These CD8+ T cells retained functionality across all age groups, and showed evidence of memory "inflation" only in later adult life.

Conclusion

CMV consistently elicits a very strong CD8+ T cell response in infants and large pools of CMV specific CD8+ T cells are maintained throughout childhood. The presence of CMV may considerably mould the CD8+ T cell compartment over time, but the relative frequencies of CMV-specific cells do not show the evidence of a population-level increase during childhood and adulthood. This contrast with the marked expansion ("inflation") of such CD8+ T cells in older adults. This study indicates that large scale analysis of peptide specific T cell responses in infants is readily possible. The robust nature of the responses observed suggests vaccine strategies aimed at priming and boosting CD8+ T cells against major pathogens (including HIV, malaria and CMV itself) could be successful in this age-group.     

From descriptive to predictive distribution models: a working example with Iberian amphibians and reptiles

Background

The two sympatric species of Tunisian desert ants, Cataglyphis bicolor and C. mauritanica, do not exhibit any differences in their foraging ecology, e.g. in food preferences and in their spatial and temporal activity patterns. Here we show that instead the two species markedly differ in their life histories.

Results

We analysed mtDNA of specimens that were collected along a 250-km transect. C. bicolor exhibited a genetically unstructured population (with the genetic and geographic distances among colonies not being correlated). On the contrary the populations of the polygynous C. mauritanica were clearly structured, i.e. exhibited a strong correlation between genetic and geographic distances. This difference is in accordance with large queen dispersal distances due to far-reaching mating flights in C. bicolor and small queen dispersal distances due to colony foundation by budding in C. mauritanica. Furthermore, wherever we found populations of both species to coexist within the same habitat, the habitat was used agriculturally. Mapping nest positions over periods of several years showed that plowing dramatically decreased the nest densities of either species.

Conclusion

We conclude that owing to its greater queen dispersal potential C. bicolor might be more successful in quickly re-colonizing disturbed areas, while the slowly dispersing C. mauritanica could later out-compete C. bicolor by adopting its effective nest-budding strategy. According to this scenario the observed sympatry of the two species might be an intermediate stage in which faster colonization by one species and more powerful exploitation of space by the other species have somehow balanced each other out. In conclusion, C. bicolor and C. mauritanica represent an example where environmental disturbances in combination with different life histories might beget sympatry in congeneric species with overlapping niches.     

In vivo analysis of fracture toughness of thyroid gland tumors

Background

Human solid tumors that are hard or firm on physical palpation are likely to be cancerous, a clinical maxim that has been successfully applied to cancer screening programs, such as breast self-examination. However, the biological relevance or prognostic significance of tumor hardness remains poorly understood. Here we present a fracture mechanics based in vivo approach for characterizing the fracture toughness of biological tissue of human thyroid gland tumors.

Methods

In a prospective study, 609 solid thyroid gland tumors were percutaneously probed using standard 25 gauge fine needles, their tissue toughness ranked on the basis of the nature and strength of the haptic force feedback cues, and subjected to standard fine needle biopsy. The tumors' toughness rankings and final cytological diagnoses were combined and analyzed. The interpreting cytopathologist was blinded to the tumors' toughness rankings.

Results

Our data showed that cancerous and noncancerous tumors displayed remarkable haptically distinguishable differences in their material toughness.

Conclusion

The qualitative method described here, though subject to some operator bias, identifies a previously unreported in vivo approach to classify fracture toughness of a solid tumor that can be correlated with malignancy, and paves the way for the development of a mechanical device that can accurately quantify the tissue toughness of a human tumor.     

Does memory improve with age? CD85j (ILT-2/LIR-1) expression on CD8 T cells correlates with 'memory inflation' in human cytomegalovirus infection

CMV-specific memory CD8(+) T cells accumulate over time to reach high frequencies amongst peripheral blood lymphocytes - a phenomenon termed 'memory inflation'. Using tetramer staining on samples from a large number of subjects and multivariate regression analysis, we were able to relate this to the phenotype of CD8(+) T cells. We made the following observations: (i) CD85j (ILT-2/LIR-1) was highly expressed alongside CD57 - an established effector memory marker - on CMV-specific CD8(+) T cells; (ii) on CD8(+) T cells as a whole, with increasing age, CD57 and CD85j (ILT-2/LIR-1) expression increased whereas CCR7 expression decreased, indicating increasing maturation of the total CD8(+) T-cell compartment with age; (iii) unit increases in the percentage of CMV-specific CD8(+) T cells expressing CD57 and CD85j (ILT-2/LIR-1) were associated with incremental expansion of these T-cell populations; (iv) CMV seropositivity is associated with a marked effect on the overall phenotype of CD8(+) T cells (at any given age, CMV seropositivity is associated with an 18.7% increase in CD85j (ILT-2/LIR-1) expression); and (v) from our observations we estimated from this an apparent 'ageing effect' of CMV on CD8(+) T cells of 35.4 years. The data presented are consistent with a predictable, unidirectional and linear model of virus specific T-cell differentiation and maturation.     

Molecular phylogeny of the major arthropod groups indicates polyphyly of crustaceans and a new hypothesis for the origin of hexapods

A phylogeny of the arthropods was inferred from analyses of amino acid sequences derived from the nuclear genes encoding elongation factor-1 alpha and the largest subunit of RNA polymerase II using maximum- parsimony, neighbor-joining, and maximum-likelihood methods. Analyses of elongation factor-1 alpha from 17 arthropods and 4 outgroup taxa recovered many arthropod clades supported by previous morphological studies, including Diplopoda, Myriapoda, Insecta, Hexapoda, Branchiopoda (Crustacea), Araneae, Tetrapulmonata, Arachnida, Chelicerata, and Malacostraca (Crustacea). However, counter to previous studies, elongation factor-1 alpha placed Malacostraca as sister group to the other arthropods. Branchiopod crustaceans were found to be more closely related to hexapods and myriapods than to malacostracan crustaceans. Sequences for RNA polymerase II were obtained from 11 arthropod taxa and were analyzed separately and in combination with elongation factor-1 alpha. Results from these analyses were concordant with those derived from elongation factor-1 alpha alone and provided support for a Hexapoda/Branchiopoda clade, thus arguing against the monophyly of the traditionally defined Atelocerata (Hexapoda + Myriapoda).