Wearable home-monitoring devices acquiring various biosignals such as the electrocardiogram, photoplethysmogram, electromyogram, respirational activity and movements have become popular in many fields of research, medical diagnostics and commercial applications. Especially ambulatory settings introduce still unsolved challenges to the development of sensor hardware and smart signal processing approaches. This work gives a detailed insight into a novel wireless body sensor network and addresses critical aspects such as signal quality, synchronicity among multiple devices as well as the system's overall capabilities and limitations in cardiovascular monitoring. An early sign of typical cardiovascular diseases is often shown by disturbed autonomic regulations such as orthostatic intolerance. In that context, blood pressure measurements play an important role to observe abnormalities like hypo- or hypertensions. Non-invasive and unobtrusive blood pressure monitoring still poses a significant challenge, promoting alternative approaches including pulse wave velocity considerations. In the scope of this work, the presented hardware is applied to demonstrate the continuous extraction of multi modal parameters like pulse arrival time within a preliminary clinical study. A Schellong test to diagnose orthostatic hypotension which is typically based on blood pressure cuff measurements has been conducted, serving as an application that might significantly benefit from novel multi-modal measurement principles. It is further shown that the system's synchronicity is as precise as 30 μs and that the integrated analog preprocessing circuits and additional accelerometer data provide significant advantages in ambulatory measurement environments.
Proteolytic enzymes, which are synthesized and secreted by cells of the seminiferous tubule of the testis, have important functions in spermatogenesis. We performed metabolic studies using small peptide hormones as a substrate to investigate the activity of proteases in cultured Sertoli cells of the rat. High-performance liquid chromatographic analysis of the cell culture supernatants showed cleavage of met-and leu-enkephalin, substance P, and bradykinin. No peptidolysis was observed for the cyclic peptide oxytocin. The hormone cleavage pattern and the use of specific protease inhibitors in peptide degradation experiments demonstrated activities of several proteases in Sertoli cells. These are mainly metalloproteinases including neutral metalloendopeptidases, angiotensin-converting enzyme and aminopeptidases. In addition, activities of serine and aspartic proteases were detected. Only marginal proteolytic activities were observed in Sertoli cell conditioned supernatants, indicating that the investigated proteases are mainly located on Sertoli cell membranes. The peptide hormones used in this study have been found to play a potential role in the endocrine, paracrine or autocrine regulation of testicular cells. The membrane-associated proteases reported here may therefore be involved in the metabolism and inactivation of these peptides.
Candida oesophagitis is a common concomitant disease in neutropenic cancer patients after chemotherapie as well as in HIV-patients. In order to characterize the features of oesophagitis in each population, we reviewed the medical history and pathology records of 23 patients (18 cancer-patients, 5 HIV-patients) with culture and autopsy-proven Candida oesophagitis. Histopathological patterns of morphology, invasion, angioinvasion and inflammation were evaluated. Virtually all patients, 17/18 cancer- and 5/5 HIV-patients, had a history of previous mucosal candidosis or candidemia. There was a significant difference histopathologically in depth of invasion of the Candida-organisms between cancer and HIV-patients. Only in HIV-patients organisms were observed within the muscularis propria and the adventitia (2/5 vs 0/18; p = 0.04). The frequency of angioinvasion (12/18 vs 3/5) was similar in both groups. Neutropenia (< 500/microliter) was present in 12 (68%) of 18 cancer patients vs 0/5 HIV-patients (p = 0.01). Correspondingly there was a significant higher PMN/MN ratio in the oesophageal inflammatory infiltrate in HIV-patients, reflecting chemotherapy-induced neutropenia in cancer patients (p = 0.02). Oesophageal candidosis in HIV-patients may be highly invasive despite the presence of neutrophils. These findings suggest an impaired inflammatory response of HIV-patients to invasive candidosis, leading to impaired mucosal host defence.
Such analyses provide information about the needs of potential users and indicate how to design such technical systems. Furthermore, opportunities and challenges of the development process as well as important contextual information were identified.
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