Familiarity influences social networks in dairy cows after regrouping.

Regrouping is common practice when managing dairy cow groups, and it is known to have disruptive effects on behavior and production. The presence of a small group of familiar cows upon regrouping may provide social support and mitigate some of the negative effects. In this study we investigated (1) how regrouping affects social relationships among familiar cows and (2) if cows prefer familiar individuals over unfamiliar ones as social partners after regrouping. We used 3 established groups of cows to create 2 new groups, each containing 14 cows, using subgroups of familiar animals (i.e., 4, 6, and 4 cows) from the original groups. The new groups were similar in respect to the age, parity, and sire of cows. The frequencies of grooming and displacements were determined in the walking alley, lying stalls, and feed bunk by observing 48 h of continuous video before regrouping, directly after regrouping, and 1 wk later. First, social network analysis was applied to investigate the effects of regrouping on the relationships within the subgroups of familiar cows. Second, we determined if familiar cows were more or less connected than would be expected by chance (i.e., assortment), considering displacement, grooming, and feed bunk neighbor networks (derived from electronic feeder data) after regrouping. Regrouping increased the number of displacements, especially in the walking alley. Within the subgroups of familiar cows, regrouping resulted in slightly more displacements, but the network structure did not change. The frequency of grooming among familiar cows remained stable across all observation periods, and the network structure was not affected by regrouping. We found positive assortment in grooming and feed bunk neighbor networks, thereby suggesting that cows preferred familiar individuals as grooming partners and feeding neighbors directly after regrouping and, to a smaller extent, 1 wk later. The effect of familiarity on displacements depended on the pen area. The weak assortment directly after regrouping at the feed bunk indicated that familiar cows displaced each other more than unfamiliar ones, possibly because they were neighbors more often. Our results indicated that a small group of familiar cows may provide ongoing social buffering after regrouping. Further research with multiple groups and larger group sizes is needed to determine whether similar effects are consistently present when groups of familiar cows are subjected to regrouping.

Refractoriness of cardiac muscle as affected by intercalated disks: a model study implications for fibrillation and defibrillation.

It is generally agreed that inhomogeneities of the recovery process in cardiac tissue play an important role in the genesis of reentrant arrhythmias. Regarding cardiac muscle as an assembly of discrete cells connected by gap junctions, differences in recovery may result from a nonuniformity of membrane or cable properties. In this study, a computer model of a one-dimensional cardiac muscle fiber including a periodic intercalated disk structure is used to study the influence of disk resistance (Rj) and stimulus strength (J) on refractoriness. Stimulating currents are applied externally in a bipolar arrangement. The basic effect of a current pulse is local de- and hyperpolarizations at the ends of an individual cell. Polarization develops very rapidly and increases with increasing values of Rj or J so that an interaction with membrane current kinetics becomes possible. When a premature stimulus is applied during repolarization of a conditioning action potential, multiple Na currents can occur, either caused by depolarization of the cathodal end of a cell or in the form of anode break excitation at the hyperpolarized end. Those currents affect the response of a fiber such that, at a given value of J, the refractory period is shortened by an increase in Rj. In a ring fiber model with different Rj values in the two halves of ring an extrastimulus timed between the refractory periods of the two branches results in a sustained circus movement. Varying stimulus strength yields an upper limit of vulnerability characterized by a "synchronized extrasystole". The ring model also implies the suppression of circus movement by an external shock. The minimal shock strength required for suppression is close to the upper limit of vulnerability. The simulations suggest that discrete effects of junctional resistance may be involved in fibrillation and defibrillation.

[Intramedullary osteosynthesis of distal metacarpal fractures with curved wires]. / Die intramedulläre Osteosynthese distaler Metakarpalfrakturen mit gebogenen Drähten.

When intramedullary pinning is used to treat metacarpal fractures, as recently described by Förstner (1994) and Foucher (1995), the closed reduction technique developed by Jahss (1938) is applied in the same way as for conservative fracture treatment. It is not always possible to achieve complete anatomical reduction using this closed technique. The intramedullary pinning technique, that we have applied since 1989, involves a Kirschner wire which is bent at one end. Apart from reducing the fracture, the pre-set Kirschner wire serves as a butressing internal fixator. The elastic clamping of the wire acts as an internal wire spring splint, permitting early mobilisation. We have operated on 62 metacarpal fractures using the above-mentioned technique over a period of 6 years until 1995. Anatomic reduction was realized in 50 of 62 fractures. In the follow-up of 32 fractures, we noticed four complications: one infection, two paraesthesias, and one non-union.

A method to reduce tension at the suture site.

Moderate-sized defects following injuries of peripheral nerves, like the median or ulnar, can be bridged instead of undergoing secondary repair with grafting, by primary or early secondary suturing using polydioxanon microbands (20 mm in length, 1 mm in width). Attached to the epineurium on both sides of the suture site, the bands help to reduce tension, thus reinforcing tensile strength. Early mobilization is possible. Primary or early secondary suturing is favored also in cases with defects up to 25 or even 30 mm, if the elasticity of the stumps permits sufficient elongation without hazard to the blood supply. Gaps of more than 30 mm require nerve grafting.

The effect of intranasal salmon calcitonin on postmenopausal bone turnover as assessed by biochemical markers: evidence of maximal effect after 8 weeks of continuous treatment.

Although treatment with intranasal salmon calcitonin (sCT) has been shown to effectively inhibit postmenopausal bone loss, there is still controversy over both timing and the duration of its application. In an open prospective study, we therefore assessed the effect of shortterm intranasal sCT on postmenopausal bone turnover, employing biochemical markers of bone metabolism. Ten early postmenopausal, previously untreated women (1-5 years after menopause) with biochemical evidence of increased bone resorption and a low bone mineral density at baseline were treated with intranasal sCT (100 IU B.I.D.) for a period of 3 months. Oral calcium (500 mg/day) was administered simultaneously, and during a further 3 month follow-up interval. Treatment with sCT resulted in a pronounced suppression of bone resorption markers with a maximum effect reached after 8 weeks of therapy: as compared to the respective baseline values, mean levels decreased by -26.2% +/- 3.4% (P < 0.001) for pyridinoline, -32.7% +/- 3.5% (P < 0.001) for deoxypyridinoline, -32.7% +/- 3.3% (P < 0.001) for hydroxyproline, and -24.1% +/- 8.2% (P < 0.001) for the amino-terminal telopeptide. In contrast, changes in bone formation markers of osteocalcin (-14.4% +/- 4.8%, P < 0.05) and C-terminal procollagen type I propetide (-7.9% +/- 3.9%, ns) were much less pronounced. Unexpectedly, after week 8 of the study all resorption markers showed a plateau and a trend to increase, although intranasal sCT was continued for a total of 12 weeks. This effect could not be attributed to the formation of anti-sCT antibodies. After cessation of treatment, both bone formation and resorption markers rapidly returned to baseline levels. Bone mineral density of both spine and hip showed no significant change during the observation period. Our results demonstrate that in postmenopausal women with a high bone turnover, intranasal treatment with 200 IU of sCT effectively reduces bone turnover and maintains bone mass, the maximum effect being reached after 8 weeks of treatment.

Parathyroidectomy in primary hyperparathyroidism: preoperative localization and routine biopsy of unaltered glands are not necessary.

BACKGROUND: An assessment was made of operative risk and outcome after parathyroidectomy for primary hyperparathyroidism. METHODS: A retrospective study was conducted in a single center university hospital in Switzerland. The 173 patients (130 women and 43 men) ranged from 17 to 89 years of age (mean, 62.0 years). No routine preoperative localization methods were used for primary neck exploration. Parathyroidectomy was performed under general anesthesia. No routine use was made of intraoperative biopsy of glands whose macroscopic appearance was normal. The 173 patients underwent 179 operations (170 primary and 9 secondary interventions). Resection of a single gland was performed in 127 cases (73.4%) and of two glands in 36 cases (20.8%). Subtotal parathyroidectomy (3 1/2 glands) was performed in 10 cases (5.8%). RESULTS: Of 170 patients with primary intervention, 164 (96.5%) were normocalcemic after operation. Six of 170 patients (3.5%) underwent early reexploration. Three additional patients underwent late secondary procedures. These nine secondary operations were successful in seven patients (78%). At follow-up (mean, 24.7 months after operation) normocalcemia was noted in 163 of 171 patients (95.3%). Persistent and recurrent hyperparathyroidism occurred in 1.2% and 3.5% of patients, respectively. Permanent postoperative hypoparathyroidism was noted in 4% (six of seven patients underwent a subtotal parathyroidectomy for multiglandular hyperplasia). Operative morbidity and mortality were 2.3% and 0.6%, respectively. CONCLUSIONS: Our surgical strategy for treatment of primary hyperparathyroidism has proved to be safe with a favorable outcome in more than 95% of patients. This was possible without the routine use of preoperative localization studies and intraoperative biopsy of macroscopically normal glands. Routine biopsy of normal-appearing glands seems to be unnecessary and may increase the risk of hypoparathyroidism.

[Tension relief in nerve sutures]. / Spannungsentlastung bei Nervennähten.

In short defects up to 25 mm following injuries of peripheral nerves, a method of suturing is outlined using two PDS-ribbons which are sutured to the epineurium, reducing tension at the site of coaptation. The ribbons are 20 mm long and 1 mm wide. They distribute and reduce the tension at the suture site and permit early mobilisation. They induce a restricted scar on the epineurium, maintaining tension relief. Of 105 nerves sutured with this method results have been obtained in 53 cases with an average follow-up time of at least 12 months. The overall results: Median nerve (N = 28) S3-4 64.5%, M3-5 82%. Ulnar nerve (N = 25) S3-4 77%, M3-5 84.5%. Clean cuts had the best results, secondary sutures (with an average interval of 30 days) were somewhat better than primary sutures.

[Thyroid gland function and endocrine orbitopathy]. / Schilddrüsenfunktion und Endokrine Orbitopathie.

Commonly the Endocrine Orbitopathy (EO) is associated with Graves' disease, but encountered also with Thyroiditis Hashimoto and hypothyroidism. The EO may coincide, precede, or appear during the endocrine dysfunction. EO and thyroid dysfunction are due to an autoimmune process caused by specific immunoglobulins G (IgG). Such IgG behave like TSH, inducing hyperthyroidism, and/or may be goitrogen or cytotoxic to thyroid cells as well as to orbital tissue. For the treatment outcome of EO an optimal hormonal thyroid status is mandatory, and a progressing malignant EO requires early, and high dose steroid treatment.

[Reposition instrument for Bennett's fracture-dislocation]. / Repositionsgerät für den Bennettschen Verrenkungsbruch.

A special hook and plate can be used to adapt small central fragments in the open reduction of Bennett's fracture-dislocation. The hook is positioned behind the small central fragment and compression exerted between the hook and a plate attached to the opposite side of the base of the first metacarpal bone using an adjustable nut, thus holding the fragments together. The reduction device simplifies X-ray controls and internal fixation with Kirschner wires.

The cell surface of isolated cardiac myocytes--a light microscope study with use of fluorochrome-coupled lectins.

In cells isolated from guinea-pig or rat ventricular muscle occurrence and distribution of carbohydrate components of the surface coat were monitored using fluorochrome-coupled lectins. Fluorescence of membrane-bound lectins was assayed by an image analysis system. The lectins ConA, WGA, sWGA, LFA and RCA-I showed specific binding to the whole myocyte surface, indicating a homogeneous distribution of alpha-mannosyl, alpha-glycosyl, N-acetylglucosaminyl, N-acetylneuraminate and beta-galactosyl residues. Binding of DBA and SBA, with specific affinity for N-acetylgalactosaminyl residues, to guinea-pig cardiac myocytes was mainly at the cell poles corresponding to intercalated discs in intact tissue. Both lectins failed to interact with rat myocytes. UEA-I, specific for alpha-L-fucose, bound slightly to rat and not to guinea-pig myocytes. Binding of PNA to guinea-pig myocytes was observed only after cleaving off sialic acids from cell surface, suggesting that sialic acids mask galactosyl-beta(1,3)-N-acetylgalactosamine residues. Specificity of lectin-cell interaction was tested by an inhibition assay where free sugars were tested for their capacity to inhibit lectin binding to the myocytes. When comparing different isolation procedures based on different proteolytic enzymes, the myocytes' affinity to any lectin was found to be qualitatively unchanged. Investigation of lectin-decorated myocytes by means of confocal laser scan microscopy showed that lectin binding sites are not confined to the cell surface but are also present in sarcolemmal invaginations, i.e. transverse tubules. This suggests that the tubular system is lined with a carbohydrate layer similar to, and continuous with, that of the peripheral cell surface.

[Reducing tension in sutures of peripheral nerves]. / Spannungsentlastung bei Nähten peripherer Nerven.

A method is presented to reinforce normal suturing techniques in median and ulnar nerve repairs at the level of the forearm or wrist. If the distance between the stumps does not exceed 20 to 30 mm the coaptation can be protected from tension by two ribbons of polydioxanone (PDS) which are sutured to the epineurium bridging the site of the suture of the nerve. PDS ribbons proved to give remarkable support to experimental nerve repairs using epineural, perineural or Tsuge suture techniques. In further experiments with tibial nerves of rats the PDS ribbon did not interfere with the nerve function or with axon sprouting. Follow-up investigations of thirty-two median and ulnar nerve injuries treated with primary or secondary interfascicular sutures using PDS ribbons of 20 mm length and 1 mm width to protect the suture line revealed satisfactory reinnervation. The late results with this method were superior to a comparable group treated with autografts.

[Calcitonin and osteoporosis--a critical review of the literature 1980-1989]. / Calcitonin und Osteoporose--Kritische Durchsicht der Literature 1980-1989.

Due to increasing old age and a prolonged life expectancy osteoporoses mainly of the involutional type have become very common and are thus of prime socio-medical importance. Recently considerable attention has been given to calcitonin as an aetiologic, prophylactic and therapeutic agent in osteoporosis. Since the subject is very controversial, the present study aims at critically evaluating the pertinent literature from 1980-1989: 1. A decreased stimulability of the thyroid C-cells and thus a diminished calcitonin secretion capacity has been demonstrated in white postmenopausal women. However an overt calcitonin deficiency cannot be considered to be the only or a major cause of the osteoporotic bone loss. 2. An increased bone loss (occurring in phases?) may be stopped by calcitonin(s) given either parentally or by the intranasal route. This pharmacologic calcitonin effect does not differ from the well-known osteoclast inhibiting effect in Paget's disease and seems to be similar to estrogen bone effects in the menopause. 3. An increase of total body calcium (TbCa) of 1-4% and of the bone mineral content (BMC) has been reported occurring within 18-24 months of calcitonin administration in overt osteoporosis. However a reinforcement of the bone structure has not been shown, further crash fractures of vertebras occurring despite calcitonin administration for up to 2 years. Within this observation period the bone volume assessed histomorphometrically did not increase, unless calcitonin was combined with phosphates which were known to induce secondary hyperparathyroidism. 4. Repeatedly an analgesic efficacy has been ascribed to calcitonins, presumably due to a direct hormonal effect on calcitonin receptors in the brain. Since the pain in osteoporosis is extremely variable and often self-limiting due to fracture healing the "calcitonin analgesia" has probably been over-estimated.

Excitation-contraction coupling in voltage-clamped cardiac myocytes.

Myocytes isolated from guinea pig ventricles were voltage-clamped using patch pipettes in the whole-cell configuration. For proper voltage control fast Na+ current was blocked by TTX or inactivated by an appropriate prepulse. Zero-load cell shortening was monitored by a photoelectric device. The mechanical response to a short depolarizing clamp was mainly a phasic (transient) contraction. Long-lasting depolarizations caused a tonic (sustained) shortening of a cell. Different clamp patterns were used to study the mode of activation of phasic contraction. 1) With a constant Ca2+ preload established by a train of conditioning pulses, the shortening-voltage relation measured with test pulses of varying height was a bell-shaped curve reflecting the slow inward current (ICa)-voltage relation. The test pulse had a striking influence on the first contraction of the following conditioning series, resulting in an S-shaped relation between post-test contraction and test potential. 2) With series of identical clamps of varying height, steady-state contraction was maximal around 40 mV and not in proportion to ICa. In these measurements Ca2+ preload was likely to increase with increasing potential. It is concluded that ICa initiates phasic contraction by inducing a release of Ca2+ from internal stores while replenishment of the stores is largely determined by an electrogenic transsarcolemmal Na+-Ca2+ exchange. The data suggest that Na+-Ca2+ exchange is not only involved in long-term changes of cardiac contractility but also in beat-to-beat regulation.

[Fibrin adhesive in the surgical treatment of pseudarthrosis of the scaphoid bone--method and results]. / Fibrinklebung bei der operativen Behandlung der Kahnbeinpseudarthrose--Methode und Ergebnisse.

In 50 cases of pseudarthrosis of the scaphoid bone the operative technique of Matti and Russe was applied using fibrin adhesive in addition to a cortico-cancellous bone graft from the iliac crest to secure the fixation of the graft. 48 patients were re-examined. 27% showed bone consolidation after 3 months, 60% after 6 months or more. The total consolidation rate was 87%. It is not quite sure whether the better results are due to fibrin adhesive or not, especially when the consolidation took place after 6 month or more.

[Closure of soft tissue defects in bone infections using free and pedicled muscle flaps]. / Versorgung von Weichteildefekten bei Knocheninfektionen durch freie und gestielte Muskelplastiken.

Over the period of three years 33 free latissimus dorsi-flaps and 23 pedicled myoplasties of various types for the coverage of large tissue and bone defects are performed. The operative technique of the free muscle transfer with microvascular anastomosis are described in detail. The postoperative management is outlined. The results of the free and pedicled muscle flaps are reported. In free transplantations the success-rate was 88% and in pedicled flaps 65% There is good evidence that bone consolidation and healing of the chronic bone infection can be improved by healthy vital soft tissue coverage. The indications for both procedures and the advantages and disadvantages of free and pedicled flaps are discussed.

Photoelectric recording of mechanical responses of cardiac myocytes.

A method to monitor contraction of isolated myocytes by transmicroscopic photometry is illustrated. Two photodiodes are mounted inside an inverse microscope used for visual control of a cell. Illumination of one diode varies in proportion to changes in cell length. The contraction signal is amplified in a comparator circuit. Spatial resolution of the device is in the order of 1 micron which corresponds to about 5% of cell shortening in the fully activated state of contraction. The method was tested on isolated myocytes from guinea-pig ventricle. Optical records of contraction in response to action potentials or during voltage clamp compare well with the contractile behavior of multicellular preparations.

Voltage clamp simulations for multifiber bundles in a double sucrose gap: radial vs. longitudinal resistance effects.

Voltage clamp responses of a single excitable fiber were simulated using a core conductor model including a high external resistance (Rs) in series to the fiber membrane to allow for intercellular clefts in a multifiber preparation. In terms of specific resistance, Rs was between 68 and 264 omega cm2. Internal resistivity (Ri) was taken to be zero or 200 omega cm. The aim of the study was to quantify the expected antagonistic effects of external and internal resistances on Na current measurements. With Ri = 0, the external resistance was found to cause a strong depression of fast inward current compared to an ideal space clamp at command potentials between -30 and 30 mV. With Ri = 200 omega cm, the depression of inward current was partially removed. The effects of Rs and Ri on membrane current measurement were illustrated by cable analysis assuming a quasi-steady state of the fiber at peak time of inward current.