Acid- and cryoactivation of renin in human plasma

Summary Inactive renin in normal human plasma was activated in vitro either by cryoactivation (incubation at 0° C/–5° C up to 3 months) or acid-activation (dialysis to pH 3.0 for 48 h followed by dialysis to pH 7.5). Plasma-renin-concentration was similar after either activation procedure (96±50µU/ml vs 100±43µU/ml). There was no further significant acid-activable renin after cryoactivation. These data suggest that conversion of inactive to active renin by optimized procedures is complete. The term total renin for activation results under these conditions seems to be valid.     

Renin release after furosemide and ethacrynic acid in man

Summary The mechanisms of renin release after furosemide (F) and ethacrynic acid (EA) in man were examined.We evaluated whether acute volume shifts within the low pressure system after F induce renin release via neural pathways.Immersion in a water-bath or beta-blockade reduced the increase of plasma renin concentration after F but not after EA.It is concluded that acute renin release after F but not after EA in man is partially due to neurally mediated reflexes originating from volume receptors in the cardiopulmonary area.     

Breath testing as potential colorectal cancer screening tool

Although colorectal cancer (CRC) screening is included in organized programs of many countries worldwide, there is still a place for better screening tools. In this study, 418 breath samples were collected from 65 patients with CRC, 22 with advanced or nonadvanced adenomas, and 122 control cases. All patients, including the controls, had undergone colonoscopy. The samples were analysed with two different techniques. The first technique relied on gas chromatography coupled with mass spectrometry (GC‐MS) for identification and quantification of volatile organic compounds (VOCs). The T‐test was used to identify significant VOCs (p values < 0.017). The second technique relied on sensor analysis with a pattern recognition method for building a breath pattern to identify different groups. Blind analysis or leave‐one‐out cross validation was conducted for validation. The GC‐MS analysis revealed four significant VOCs that identified the tested groups; these were acetone and ethyl acetate (higher in CRC), ethanol and 4‐methyl octane (lower in CRC). The sensor‐analysis distinguished CRC from the control group with 85% sensitivity, 94% specificity and 91% accuracy. The performance of the sensors in identifying the advanced adenoma group from the non‐advanced adenomas was 88% sensitivity, 100% specificity, and 94% accuracy. The performance of the sensors in identifying the advanced adenoma group was distinguished from the control group was 100% sensitivity, 88% specificity, and 94% accuracy. For summary, volatile marker testing by using sensor analysis is a promising noninvasive approach for CRC screening.     

Cardiovascular and adrenal sensitivity to angiotensin II in essential hypertension

Summary Regulation of aldosterone secretion by sodium chloride is impaired in a group of essential hypertensives: high-salt diet fails to suppress aldosterone in these patients despite low renin values. The mechanism of this impaired regulation of aldosterone has not been clarified so far. We tested the sensitivity of aldosterone secretion and blood pressure to A II in 20 normotensive controls (aged 20–60, MAP 92±3 mm Hg), in ten normotensives with one or two parents with hypertension, and in 21 patients with essential hypertension (aged 17–65, MAP 119±4 mm Hg). After a period of 6 days on high-salt intake (300–320 mEq Na⁺/day), A II (0.1, 0.5, 1.0 and 2.0 ng/kg/min) was infused, each concentration for 30 min. According to aldosterone excretion during sodium loading, patients were divided into group A with complete suppression (n=12, aldosterone excretion 3.6±0.4 µg/day) and in group B with insufficient suppression (n=9, aldosterone excretion 15.5±2.3 µg/day). Despite similarly low plasma renins, rise of serum aldosterone levels during A II infusion was significantly higher in group B patients than in group A patients and normotensive controls. Rise in mean arterial blood pressure, however, brought about by graded A II infusion was similar in both groups of hypertensives and in normotensive controls. The results demonstrate an increased adrenal sensitivity to A II in a subgroup of essential hypertensives only. A similar adrenal hypersensitivity to A II found by others in patients with hyperaldosteronism due to adrenal hyperplasia supports the hypothesis that the same mechanism underlies both disorders.Abbreviations MAP mean arterial blood pressure - A II Angiotensin II Dedicated to Prof. Dr. W. Kaufmann on the occasion of his 60^th birthday     

Similar outcomes between two-stage revisions for infection and aseptic hip revisions

Purpose

Two-stage revision hip arthroplasty using an antibiotic-loaded spacer is the most widely performed procedure for infected hip arthroplasties. The clinical outcome of this type of surgery compared with aseptic joint revision with exchange of femoral and acetabular components is still controversial due to the relative lack of medium- to long-term follow-up. Therefore, we analysed clinical and radiological outcomes of septic two-stage revisions compared with aseptic hip revision surgeries.

Methods

In this retrospective study we assessed 82 consecutive patients who underwent two-stage revision for septic total hip (45 patients) or one-stage aseptic revision arthroplasty (37 patients). The average follow-up was 53 months for the aseptic group and 55 months for the septic group. For clinical evaluation, we used the Harris Hip Score (HHS) and the Merle d’Aubigné and Postel score. The postoperative pain level was determined with the visual analogue pain scale.

Results

The surgeries were performed 124 months (aseptic group) and 119 months (septic group) after primary total hip arthroplasty on average. The main indications for aseptic revision surgeries were aseptic loosening (96 %), dislocation (2.2 %), and periprosthetic fracture (2.2 %). In the clinical outcome patients achieved 75.5 points in the aseptic group and 73.4 points in the septic group in the Harris Hip Score. The Merle d’Aubigné and Postel Score revealed 12.5 points for the aseptic group and 13.1 points for the septic group. Mean level of persisting pain was 0.8 (aseptic group) and 0.4 (septic group) on the visual analogue scale (VAS). Overall survival in the aseptic group was 85.6 % at 9.8 years 82.7 % at 10.1 years for the septic group, with a repeat revision rate of 8.1 % and 6.7 %, respectively.

Conclusions

Performing aseptic acetabular and femoral revision hip arthroplasty showed equal clinical outcomes in relation to septic two-stage revision hip surgeries. Our results showed a tendency for better outcome in comparison with the information given in the literature for septic and nonseptic exchange arthroplasties, including a lower rate of re-revisions.

     

Effects of vasopressin and its deamino-d-arginine analogue on renin release in the isolated perfused rat kidney

The direct action of arginine-vasopressin (AVP) and its deamino-d-arginine analogue (DDAVP) on renin release (RR) has been studied in isolated rat kidneys perfused with an electrolyte solution at constant pressure in a single-pass system. AVP and DDAVP infused at various concentrations (80 to 2100 pg/ml and 80 to 8700 pg/ml, respectively) reduced volume and increased osmolality of urine in a dose-dependent way. High doses of AVP reduced renal perfusate flow and glomerular filtration rate while DDAVP had no effect on renal haemodynamics. When vasoconstrictor doses of AVP or high concentrations of DDAVP were infused, basal RR remained unchanged. However, when RR had been stimulated by infusion of isoproterenol, vasoconstrictor doses of AVP as well as high doses of DDAVP which did not increase renal vascular resistance diminished RR by about 30% (P<0.01, andP<0.05, respectively). These results suggest that the inhibition of RR by vasopressin is not related to its vasoconstrictor action.     

Minimally invasive arthroscopy of the knee using a new 2 mm device

Arthroscopy has been evolving over the last decades, whereas arthroscopic devices have not changed much. Smaller diameter arthroscopes would potentially reduce the intraoperative trauma for cartilage and soft tissues. Two‐millimeter‐diameter arthroscopy demonstrated very good visualization and reach of intraarticular structures—similar to knee arthroscopy using a standard arthroscopic system.     

Temporary distraction and compression of a diaphyseal osteotomy accelerates bone healing

Mechanical strain during callus distraction is known to stimulate osteogenesis. It is unclear whether this stimulus could be used to enhance the healing of a normal fracture without lengthening the bone. This study tested the hypothesis that a slow temporary distraction and compression of a diaphyseal osteotomy accelerates fracture healing. Fourteen sheep underwent a middiaphyseal osteotomy of the right tibia, stabilized by external fixation. An external fixator allowed either a temporary axial distraction (TD group; n = 6) or a constant fixation (C group; n = 8). Distraction began 7 days postoperatively at a rate of 0.5 mm twice per day for 2 days with subsequent shortening of 1.0 mm twice on the third day. The procedure was repeated four times. Fluorochrome labeling was performed postoperatively. After 8 weeks the sheep were sacrificed and healing was evaluated using densitometric, biomechanical, and histological methods. Bending stiffness of the tibiae after 8 weeks was 58% higher in the TD group than in the C group. The volume of the periosteal callus was significantly (p = 0.05) higher in the TD group (3.9 cm³) than in the C group (2.7 cm³). There was 20% more bone in the fracture gap of the TD group than the C group. There was a significantly higher bone formation rate in the TD group than in the C group. This study demonstrated the feasibility of fracture healing stimulation by the temporary application of distraction and compression. © 2008 Orthopaedic Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:772–777, 2008