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.

DDT: interaction with nerve membrane conductance changes.

The falling phase of action potentials of lobster giant axons is prolonged by DDT; finally a plateau phase is produced like cardiac action potentials. In axons poisoned with DDT, peak transient (sodium) currents associated with step depolarizations are turned off very slowly, and steady-state (potassium) currents are markedly suppressed. These two changes would cause the prolongation of action potentials and are considered the major ionic mechanisms of DDT action.

Saxitoxin and tetrodotoxin: comparison of nerve blocking mechanism.

Saxitoxin at concentrations of 3 x 10(-8) to 3 x 10(-7) mole per liter blocks the conduction of lobster giant axon with no change in resting potential. Recovery of washed axons is faster in those that had been treated with saxitoxin than it is in those that were treated with tetrodotoxin. Peak transient increase in nerve membrane conductance is selectively blocked by saxitoxin with no change in late steady-state increase in conductance. The major mechanism of saxitoxin blockage is the same that of tetrodotoxin blockage.

Renal effects of calcitonin and parathyroid extract in man. Studies in hypoparathyroidism.

To clarify the controversial renal action of calcitonin (CT) and a possible interrelationship between CT and parathyroid hormone, eight patients with untreated surgical hypoparathyroidism were studied. Various calcitonins, i.e. extracted porcine, synthetic porcine, synthetic human, and synthetic salmon CT in doses of 150 Medical Research Council U or 1.5 mg were infused over a 3 hr period. Subsequently, six of the same subjects received 500 USP U parathyroid extract (PTE) (Eli Lilly & Co., Indianapolis, Ind.) in 3 hr and later a combination of CT and PTE. In addition, two patients were given an infusion of ammonium phosphate with the aim of producting a phosphaturia of comparable degree as seen after CT and PTE, thus differentiating hormonal from nonhormonal influences on cation excretion. A protocol of serial clearance (C) studies using the patients as their own controls was followed. Serum and urinary inorganic phosphate (P), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), and creatinine (Cr) were determined and the clearance values calculated. All CT peptides caused a uniform, immediate and significant increase of C(P), C(Na), C(K), C(Ca), and C(Mg), PTE evoked a rise of C(P), C(Na), and C(K), but C(Ca) and C(Mg) were reduced, the Ca and Na figures being not statistically significant. The administration of both CT and PTE resulted in a summation of individual hormone effects on Ca and Mg excretion. Phosphate infusion on the other hand induced an isolated phosphaturia but no concomitant changes of the urinary cations.The hypoparathyroid data demonstrate that calcitonin enhances urinary elimination of P, Na, K, Ca, and Mg independently of parathyroid action, CT and PTE act qualitatively similarly on P, Na, and K excretion, while an antagonism seems to exist for the renal handling of Ca and Mg.

Interaction of DDT with the components of lobster nerve membrane conductance.

The falling phase of action potential of lobster giant axons is markedly prolonged by treatment with DDT, and a plateau phase appears as in cardiac action potentials. Repetitive afterdischarge is very often superimposed on the plateau. Voltage-clamp experiments with the axons treated with DDT and with DDT plus tetrodotoxin or saxitoxin have revealed the following: DDT markedly slows the turning-off process of peak transient current and suppresses the steady-state current. The falling phase of the peak transient current in the DDT-poisoned axon is no longer expressed by a single exponential function as in normal axons, but by two or more exponential functions with much longer time constants. The maximum peak transient conductance is not significantly affected by DDT. DDT did not induce a shift of the curve relating the peak transient conductance to membrane potential along the potential axis. The time to peak transient current and the time for the steady-state current to reach its half-maximum are prolonged by DDT to a small extent. The finding that, under the influence of DDT, the steady-state current starts flowing while the peak transient current is partially maintained supports the hypothesis of two operationally separate ion channels in the nerve membrane.

Polyendocrine deficiency syndrome. Occurrence in a patient with depressed IgA titers receiving phenytoin.

A 35-year-old woman had an addisonian crisis and primary adrenal, ovarian, and thyroid failures were detected. Antibodies against the adrenal glands and the thyroid were found, together with consistently low IgA levels. The patient had been receiving phenytoin, a drug known to induce an IgA deficiency, for 20 years. The question arises as to whether this substance was responsible for an immunological defect leading to an autoimmune process that damaged the adrenal glands, the ovaries, and the thyroid.

Cyproteroneacetate and ACTH adrenal function.

Cyproteroneacetate, an antiandrogenic and gonadotropin-inhibiting steroid, has a marked ACTH suppressive effect. In rats, adrenal atrophy and severe impairment of ACTH and corticosterone responses to stress are induced by a 10-day treatment with 3-0.75 mg/100 g BW cyproteroneacetate/day. Two weeks after cessation of treatment, the ACTH adrenal system has not yet recovered. The ACTH suppression is evident 6 h after a single dose. In 25 human volunteers, a single dose of 200 mg cyproteroneacetate impaired their ACTH and 11-deoxycorticosteroid response to 1 g metyrapone. A similar impairment was seen in 12 women on sequential treatment with cyproteroneacetate and ethinyl estradiol. In 4 out of 11 children treated for precocious puberty, random plasma ACTH and cortisol measurements, cortisol responses to ACTH, and ACTH and cortisol responses to insulin-induced hypoglycemia revealed severely impaired ACTH adrenal function. Questionable impairment was found in 2 out of 11 and normal function in 5 out of 11 children. In 10 patients with endogenous elevated plasma ACTH, 10 days of treatment with cyproteroneacetate, in addition to the steroid substitution, diminished the morning plasma ACTH levels. It is concluded that cyproteroneactate has a pronounced ACTH-suppressive effect. The individual susceptibility of treated patients varies and the effect is dose dependent. A cortisol-like effect must be assumed, because cyproteroneacetate-treated animals and patients under therapy can withstand stress situations without signs of adrenal insufficiency. ACTH adrenal function must, however, be closely watched in treated patients and steroid cover must be considered in conditions of stress. Great care has to be taken when the drug, with its own "stress-protective" effect, is withdrawn. The recovery of ACTH adrenal function may take several months.

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.

The metabolic balance technique: a critical reappraisal.

Twenty-six metabolic balance studies (MBS) of Ca, Mg, and P have been conducted in 11 postmenopausal women with osteoporosis and in 4 patients suffering from Paget's disease of bone. Subjects were given a liquid formula diet (LFD) matched as closely as possible to the patient's home diet. Studies lasted for 25 days, separated into 5-day periods by a carmine marker combines with Cr2O3 as continuous fecal marker. The balance studies were combined with a tracer technique using 47Ca to detect a possible loss of Ca by perspiration. The reliability of analytical methods necessary for mineral balances was tested. In 22 of the 26 MBS a steady state (SS) reflecting the patient's regular living conditions was demonstrated, while a non-SS situation possibly due to changes of physical activity was seen in four instances. The overall precision and accuracy of this balance method for Ca and P was found to be better than plus or minus 50 mg/day after four periods and plus or minus 40 mg/day after five periods, as related to an average daily intake of 920 mg Ca and 1230 mg P. For Mg (intake 190 mg/day), a precision of plus or minus 10 mg/day was recorded. The dermal loss of Ca was found to be less than 20 mg/day. As shown for Ca, Mg and P, the precision of a balance study is only little enhanced when the investigation is continued for more than four periods. At the present time is not possible to predict non-SS situations before starting such a study but a simple formula is proposed to detect those which were not performed under SS conditions.

Bone remodeling and calcium metabolism: a correlated histomorphometric, calcium kinetic, and biochemical study in patients with osteoporosis and Paget's Disease.

The extent to which histomorphometric analysis of bone biopsies correlates with Ca kinetic and biochemical parameters to reflect true bone formation and resorption in adult man remains an unsolved issue. Two groups of patients with either low (osteoporosis), (n = 15) or high (Paget's disease, n = 6) bone turnover were studied before and after sodium fluoride (NaF) and diphosphonate (EHDP) treatment, respectively. Histomorphometry of iliac crest biopsies permitted precise quantitation of the osteoblast layers (SVab), osteoid seams (SVos), the number of osteoclasts (NAocl) and the Howship's lacunae (SVhl). These determinations were correlated with serum alkaline phosphatase (aPh), urinary hydroxyproline (HyPro), Ca accretion rate (Vo+), and Ca mobilization rate (Vo-). In both patient groups bone formation indices were significantly correlated: SVob/Vo+, r = 0.85; SVos/Vo+, r = 0.83; and aPh/Vo+, r = 0.97. Provided that bone matrix formation and mineralization progess at the same rate, bone formation may be assessed by measuring either aPh, Vo+, SVob, or SVos. From these correlations it is not possible to draw any conclusions regarding the absolute "true" value of bone formation, be it in terms of Ca kinetics, alkaline phosphatase, or histomorphometry. However, since Vo+ retains its proportionality to all the other bone formation parameters tested, the so-called "slow exchange," which refers to pure physicochemical Ca exchange processes in the bone mineral, does not perturb Vo+ in an unsystematic way. Vo+ as well as aPh and histomorphometric indices are thus reliable, though not absolute indices of bone formation. Bone resorption indices correlated less well than bone formation indices: NAocl/Vo-, r = 0.68 and SVhl/Vo-, r = 0.63 with both groups. In the osteoporotic group, a negative correlation existed between the empty Howship's lacunae SVhe and Vo+, r = -0.62. Consequently, the overall extent of Howship's lacunae SVhl is influenced both by bone resorption and bone formation. On the other hand, the best correlation of HyPro was with the sum of Vo+ and Vo-, r = 0.97, confirming that HyPro is a sensitive index for the change of bone turnover.

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.

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.

Voltage clamp simulations for multifiber bundles in a double sucrose gap: cable complications.

A theoretical model is presented for voltage clamp of a bundle of cylindrical excitable cells in a double sucrose gap. The preparation in the test node is represented by a single one-dimensional cable (length/diameter ratio approximately) with standard Hodgkin-Huxley kinetics for transmembrane Na current. Imperfections of voltage control due to internal (longitudinal) resistivity and external (radial) resistance in series to the membrane are analysed. The electrical behavior of a fiber is described by the cable equation with appropriate boundary conditions and subsidiary equations reflecting the membrane characteristics. Membrane voltage and current distribution in response to a step command was obtained by numerical integration. The results are described in two papers. The present paper deals with the effect of internal resistivity with the external resistance being neglected. The closed loop response of a fiber displays a strong tendency to oscillate. To stabilize the system a phase lead was inserted and the gain of the control amplifier was reduced. Conditions for stability were examined by Nyquist analysis. When the Na system was activated by a command pulse below ENa, a voltage gradient developed between a depolarization (relative to the command signal) at the end where voltage was monitored and a hyperpolarization at the site of current injection. In spite of a poor voltage control the total measured current appeared to have a smooth transient. With large voltage gradients a small, second inward current was seen. At a low (high) Na conductance maximum peak inward current was larger (smaller) that the current expected from ideal space clamping.

[Food analysis for balance studies, especially calcium, magnesium, phosphorus and nitrogen]. / Lebensmittelanalysen für Bilanzuntersuchungen, speziell Kalzium, Magnesium, Phosphor und Stickstoff

The calcium-, magnesium-, phosphorus-, nitrogen- and water-contents have been estimated in raw and processed foods (bread and sausages). These results were then compared with the data in food tables. Surprisingly small differences were recorded, since content-deviations of processed foods are equalized in a whole day menu. Thus, food tables proved to be reliable for the calculation of balance and test diets.

[PDS splint in the treatment of fractures]. / PDS-Splinte zur Frakturbehandlung.

Polydioxanon-splints have been used instead of Kirschner-wires in 13 cases for the treatment of fractures of the base or head of phalanges and metacarpals and also, in conjunction with intraosseous suture wires, to stabilize the bones in replantation surgery.

[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.

[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.

[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.

[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.

[First experiences with the external mini-fixator of Jaquet (author's transl)]. / Erste Erfahrungen mit dem Minifixateur externe nach Jaquet.

The external mini-fixator of Jaquet is a new way for external stabilization in hand surgery. The technique of applying the external mini-fixator is described and the results in the treatment of 23 cases of infected non-unions, non-unions with defect and arthrodeses are reported.