Which is the function of a martin‐gruber connection?

Clinical and diagnostic variations may occur due to the variable presence of a connection between the median and ulnar nerves in the forearm (Martin‐Gruber anastomosis). This incidence has a wide range at 7%–40%. Most commonly, the connection between the nerves is considered to be composed of motor fibers; although, a sensory role has also been described. It is important to note that the number of axons, or the nature of the fibers in this connection, have not yet been elucidated. Fifty upper limbs were examined evaluating morphometric characteristics of the Martin Gruber connection, dissected out, sectioned, and immunohistochemically stained for choline acetyltransferase (ChAT) and analyzed with ImageJ^©. The connection was observed in 32% of all cases (16/50). The nerve connections were identified as those in Pattern 1 group (12%‐type 1b, 19%‐type 1a, and 69%‐type 1c) and contained motor (ChAT positive) fibers (40.42 ± 10.5% per connection) with three to four fascicles in each. No statistically significant differences were found according to sex, side, or laterality. There were statistically significant differences in the percentages of ChAT positive fibers; however, this was dependent on the distribution being greater in those not distributed zonally. The presence of this connection is prevalent in almost a third of the cadavers dissected; the understanding of this complex composition in sensory and motor fibers allows for the optimization of diagnosis and treatment of certain median‐ulnar nerve injuries. Clin. Anat. 32:501–508, 2019. © 2019 Wiley Periodicals, Inc.     

Parachordoma or chordoma periphericum? Case report of a tumor of the thoracic wall

We report the findings from an aspiration biopsy and resection of a chordoma-like tumorous mass in the wall of the thorax of a 36-yr-old man with immunohistochemical, ultrastructural, and cytogenetic studies. The 4-cm oval tumor was an incidental finding on physical examination, and no other lesions were identified after comprehensive radiologic studies. The aspirate was composed of sheets and nests of cells with distinct borders in a myxoid and fibrillary extracellular matrix. The neoplastic cells were uniform and round or polygonal with abundant pale blue vacuolated cytoplasm and small round, central or eccentric nuclei. On electron microscopy, mitochondrial rough endoplasmic reticulum complexes were seen in neoplastic cells. These features were similar to those of a conventional chordoma. However, the cytogenetic pattern, 43, XY ,-1, -2, der (5)t(1p;5q), -6, add(8p) ,add(10q), was not typical. In addition, the neoplastic cells were positive for vimentin, S-100, AE1/AE3, CAM 5.2, and CK 19; were focally positive for EMA and smooth muscle actin; and were negative for cytokeratin 1 and 10 (34 beta E12), CK 7, CK 8 (35H 11B), CK 17, and CK 20. The cytogenetic and immunohistochemical patterns were different from conventional chordoma and its peripheral counterpart, chordoma periphericum, suggesting the diagnosis of parachordoma. To the best of our knowledge, this is the first report of fine-needle aspiration of this newly defined and rare entity.     

What is the role of tropomyosin in the regulation of muscle contraction?

Journal of Muscle Research and Cell Motility -     

Evaluation of the renal function in type 2 diabetes: clearance calculation or cystatin C?

Screening for diabetic nephropathy is usually done by albuminuria/24h and the use of creatinine clearance. The objective of this study was to evaluate the renal function in Type 2 diabetes by using different formulas of creatinine clearance and to assess the contribution of cystatin C; 83 adults with type 2 diabetes (23 men and 60 women) and 83 adult controls (40 men and 43 women) were studied. Biochemical parameters were determinated on Coba 6000? (Roche diagnostics). Diabetics showed a significant increase in blood glucose, cholesterol, triglycerides, LDLc, the ApoB, Lp(a), urea, uric acid, creatinine and cystatin C and lower HDLc. Cystatin was increased in patients with degenerative complications and in hypertensive patients. We found strong correlations of cystatin C with creatinine (r = 0.9454), urea (r = 0.8999) and uric acid (r = 0.8325). We found a significant exponentially increase of creatinine and cystatin C from one stage to another. Cystatin C has a strong association with MDRD (r = 0.8086) and CG (r = 0.7915) and a low one with creatinine clearance (r = 0.1044). In conclusion, the use of cystatin C for screening and early treatment of incipient diabetic nephropathy appears to be adequate. CG and MDRD formulas still hold their place, in regards to the classical determination of creatinine clearance, to monitor patients.     

Can muscle shortening alone, explain the energy cost of muscle contraction in vivo?

Purpose

Decreased whole-body energy cost of running has been associated with an increased Achilles tendon stiffness. It is usually assumed that this lower energy cost can be attributed to less muscle fascicle shortening with a stiffer tendon. Increased fiber shortening is an important determinant of muscle energetics in vitro. However, other factors, like increased muscle activation may be important when considering whole muscle energetics in vivo.

Methods

To determine the effects of a small additional muscle shortening on skeletal muscle energy requirement, 19 subjects performed 30 plantarflexions on two separate occasions: isometric (ISO) and isokinetic (KIN, 6.98 rad s^–1), each with a target of 50 % of maximum isometric torque. Medial gastrocnemius muscle fascicle length (FL) was measured by ultrasound and rate of oxyhemoglobin (HbO₂) desaturation was measured during blood flow occlusion using near-infrared spectroscopy.

Results

KIN resulted in significantly greater muscle shortening (23.8 ± 1.3 mm) than ISO (18.3 ± 1.0 mm, p < 0.001, mean ± SEM), and greater shortening velocity (KIN = 2.5 ± 0.3 FL s^–1, ISO = 1.1 ± 0.1 FL s^–1, p < 0.001). Rate of HbO₂ desaturation was 19 ± 7 %, greater in KIN than ISO (p < 0.01), despite 19 ± 2 % lower mean torque (p < 0.001) and 9.8 ± 1.6 Nm s lower mean impulse per contraction (p < 0.001) in KIN compared to ISO. Root mean square for EMG was significantly greater (p < 0.05) during KIN (73 ± 3 %) than during ISO (63 ± 2 %).

Conclusion

These results illustrate that muscle energy requirement is greater when muscle fascicle shortening and/or velocity of shortening is increased, and suggest that greater activation contributes to that increased energy requirement.     

Aponeurosis linguae—Myocutaneous or myotendinous junctions of skeletal muscle fibres in the human tongue?

The morphology of the more superficial tissue of the human tongue was investigated and discussed with the clinical appearance of fissures. Three regions could be distinguished according to the presence and shape of the aponeurosis linguae: the central region showed a thick aponeurotic plate with myotendinous muscle fibre insertions. The lateral region showed still an aponeurosis linguae but of reduced thickness and without muscle insertions. The edge‐wise and lower region showed no aponeurosis linguae but a fatty subcutis and myocutaneous muscle fibre insertions lacking specific molecules of myotendinous junctions. This system of partially developed exoskeleton seems to underlie but not to be involved in tongue fissures, which are more superficial within the epidermis and dermis.     

Familial occurrence of multiple pterygium syndrome: expression in a heterozygote of the recessive form or variability of the dominant form?

We report on a case with apparently familial multiple pterygium syndrome (MPS). The proposita was a 3-year-old girl with classical symptoms of MPS. A careful clinical examination of the father disclosed the presence of few minor signs of the syndrome, including difficulty in opening the mouth widely, scoliosis, pectus excavatum, hands with slight cutaneous syndactyly, and bilateral single palmar creases. The radiograph of the hands disclosed malformed carpal bones and an altered metacarpal-phalangeal pattern. The father shows limited symptoms, which has been reported before in the autosomal dominant form of MPS. However, it is also possible that he is showing a heterozygous state of the autosomal recessive form of MPS. In conclusion, we emphasize the importance of examining accurately the parents of a child who has classical MPS phenotype, even those with normal stature and an absence of facial anomalies.     

Different Evolutionary Histories of the Coagulation Factor VII Gene in Human Populations?

Immoderate blood clotting constitutes a risk factor for cardiovascular disease in modern industrialised societies, but is believed to have conferred a survival advantage, i.e. faster recovery from bleeding, on our ancestors. Here, we investigate the evolutionary history of the Coagulation Factor VII gene (F7) by analysing five cardiovascular-risk-associated mutations from the F7 promoter and nine neutral polymorphisms (six SNPs and three microsatellites) from the flanking region in 16 populations from the broader Mediterranean region, South Saharan Africa and Bolivia (687 individuals in total). Population differentiation and selection tests were performed and linkage disequilibrium patterns were investigated. In all samples, no linkage disequilibrium between adjacent F7 promoter mutations −402 and −401 was observed. No selection signals were detected in any of the samples from the broader Mediterranean region and South Saharan Africa, while some of the data suggested a potential signal of positive selection for the F7 promoter in the Native American samples from Bolivia. In conclusion, our data suggest, although do not prove, different evolutionary histories in the F7 promoter region between Mediterraneans and Amerindians.     

Utility (or futility?) of electrodiagnosis in thoracic outlet syndrome

The objective diagnosis of thoracic outlet syndrome (TOS) remains a challenge. The purpose was to present our experience and discuss the utility of electromyography, electroneurography and somatosensory evoked potentials after ulnar nerve stimulation in patients with surgically verified neurovascular compression at the thoracic outlet. Twenty patients (median age 29.5, 16 women) with operatively verified neurovascular compression by a cervical rib or band were examined. All complained of pain and paraesthesias in the hand. In 12 vasomotor disturbances (pallor or lividity, low skin temperature, Raynaud's phenomenon) were also observed. Clinical diagnosis was supported by the provocative tests (Adson, Wright, costoclavicular) in 14persons. Neurologic signs were present in 2 patients in "pseudoulnar" distribution. Anterior scalenectomy was performed with success in 15 cases, 4 remained unchanged and 1 worsened. Electrodiagnostic tests were normal in all 18 patients without neurologic signs. We note a tendency for the digital nerves sensory action potentials in patients with TOS to be higher than usual It is concluded that electrodiagnosis is useless in confirming the presence of TOS, but it is very useful to exclude other painful conditions that require other treatments (carpal and cubital tunnel syndromes, cervical radiculopathies etc).     

Uterus-like mass in the uterine cervix: superficial cervical endometriosis with florid smooth muscle metaplasia?

This study describes a 47-year-old woman, gravida 2, para 2, with a uterine polypoid mass. The 25-mm mass, which was growing into the endocervical canal, had a central cavity lined with endometrium and surrounded by smooth muscle layers. It strongly resembled a miniature uterus. It is concluded that the mass represented superficial cervical endometriosis with florid smooth muscle metaplasia of endometrial stromal cells.     

End of life in ICU--care of the dying or 'pulling the plug'?

This study, a modified subsection of the European ETHICUS study on End-of-Life (EOL) Decision Making in the Intensive Care Unit (ICU), examines the pattern of limiting futile life-sustaining therapies in an Irish ICU including the practice of withdrawing mechanical ventilation in anticipation of death. 1146 patients were admitted to the Mater Hospital, Dublin ICU from 1/9/1999 to 30/6/2000 and all 126 patients who died in ICU were included. EOL categories were prospectively defined (by Ethicus methodology) as cardiopulmonary resuscitation (CPR); brain death; withholding (WH); withdrawing (WD) life sustaining therapy and active shortening of the dying process (SDP). Complete data were obtained for 122 of the 126 patients who died during this period. 45 patients (36%) had therapy withheld, 40 (33%) had therapy withdrawn, 26 (21%) had unsuccessful CPR and 11 (10%) were Brain Dead. SDP was not performed. In total, 85 patients had a limitation of life sustaining therapy. CPR was the main therapy withheld (96% of WH/WD patients). Inotropic infusions were limited (WH or WD) in 40/85 (47%) of patients. Fluids, feeding and oxygen were rarely withdrawn (2.4%, 6%, 4.8% respectively). Twenty-two patients had two or more EOL decisions. Tracheal extubation or withdrawal of ventilation was less frequent (16.4%) but more common if a second EOL decision was made. No patient had sedation withdrawn or decreased. Eight patients of 85 (9%) had sedation increased. The study demonstrates that EOL decision making is common (69% of deaths and 7.4% of ICU admissions) in Ireland and demonstrates that the pattern of treatment limitation relates primarily to cardiovascular and other treatments and less to respiratory life sustaining treatment. Artificial nutrition and hydration were rarely withdrawn.     

What evidence implicates airway smooth muscle in the cause of BHR?

Bronchial hyperresponsiveness (BHR), the occurrence of excessive bronchoconstriction in response to relatively small constrictor stimuli, is a cardinal feature of asthma. Here, we consider the role that airway smooth muscle might play in the generation of BHR. The weight of evidence suggests that smooth muscle isolated from asthmatic tissues exhibits normal sensitivity to constrictor agonists when studied during isometric contraction, but the increased muscle mass within asthmatic airways might generate more total force than the lesser amount of muscle found in normal bronchi. Another salient difference between asthmatic and normal individuals lies in the effect of deep inhalation (DI) on bronchoconstriction. DI often substantially reverses induced bronchoconstriction in normals, while it often has much less effect on spontaneous or induced bronchoconstriction in asthmatics. It has been proposed that abnormal dynamic aspects of airway smooth muscle contraction—velocity of contraction or plasticity-elasticity balance—might underlie the abnormal DI response in asthma. We suggest a speculative model in which abnormally long actin filaments might account for abnormally increased elasticity of contracted airway smooth muscle.