Ex Vivo Evaluation in Normal Dogs of Insulin Released by a Bioartificial Pancreas Containing Isolated Rat Islets of Langerhans

In bioartificial pancreatic systems, isolated islets of Langerhans are protected against immune rejection by an artificial membrane, permeable to glucose and insulin, but not to immunoglobulins and lymphocytes. Some of these devices, referred to as vascular systems, are set up to be connected to a vascular site in the recipient, with blood circulating in contact with one side of the membrane, and the islets on the other side. Such a bioartificial pancreas, containing isolated rat islets of Langerhans, was connected to an arteriovenous shunt of a normal anesthetized dog. The aim of this experiment was to investigate the kinetics of the insulin secretory response of the system to a glucose load. Glucose was infused upstream of the system, increasing the glucose concentration inside the bioartificial pancreas from 7 to 14 mmol/l, without altering the blood glucose concentration of the dog. Insulin concentration was determined simultaneously upstream and downstream of the bioartificial pancreas. Insulin production was calculated by multiplying the difference between these values by the blood flow rate. Blood flow rate (Q) was estimated from the change in the glucose concentration produced by the glucose infusion using a mass transfer analysis derived from Fick's principle. Insulin production increased from 20 +/- 8 to 59 +/- 15 microU/100 islets/min within 15 min following the beginning of the stimulation (n = 6, p less than 0.05). Five min after the end of the stimulation, insulin production decreased from 75 +/- 13 to 50 +/- 9 microU/100 islets/min (p less than 0.05) to reach the basal level (21 +/- 3 microU/100 islets/min) 30 min after the end of the glucose stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)     

替牙(牙合)时期前牙反(牙合)矫治中弓丝弯制的探讨

目的　探讨在“2× 4”矫治技术中弓丝弯制的方法及原理。方法　替牙牙合时期前牙反牙合患者 2 4例 ,使用粗弓丝 ,在其弓丝上弯制各种曲形 ,并根据不同错牙合类型 ,处理各种曲与牙齿、带环关系 ,防止出现磨牙旋转移动等异常。结果　 2～ 6个月纠正反牙合 ,2 4例替牙牙合时期反牙合患者得以早期矫治。结论　本方法矫治时间短 ,效果明显 ,操作简单 ,能够达到较为理想的矫治效果     

Monoclonal antibodies to canine intra-acrosomal sperm proteins recognizing acrosomal status during capacitation and acrosome reaction

Summary.  Monoclonal antibodies Ds-1 and Ds-2 specifically labelling dog sperm acrosome were prepared by immunization of mice with acetic acid extracts of dog spermatozoa. Electron microscopy and indirect immunofluorescence localized the site of Ds-1 and Ds-2 proteins inside the acrosomal vesicle. Ds-1 antibody detected 55, 76, 115, 120 and 190kDa proteins under non-reducing conditions, and 73 kDa and 54 kDa proteins after reduction (p73/Ds-1 and p54/Ds-1). 92 kDa and 40 kDa proteins recognized by Ds-2 (p92/Ds-2 and p40/Ds-2) migrated at > 200 kDa in the absence of reducing agent. In vivo , p73/Ds-1 and p54/Ds-1 are therefore likely to be present both in free and complexed form, while all of p92/Ds-2 and p40/Ds-2 form disulfide-bonded complexes. Decrease in the rate of acrosomes stained with Ds-1 and Ds-2 was correlated with the progress of capacitation resulting in the increased rate of spontaneous acrosome reactions, as suggested by a dramatic effect of A23187. Monoclonal antibody to boar acrosin (ACR-2) recognized dog sperm acrosin homologue. A higher rate of ACR-2-negative spermatozoa was observed after capacitation and A23187 treatment compared to Ds-1 and Ds-2, indicating that proteins recognized by Ds-1 and Ds-2 are localized in a specific compartment of acrosome, distinct from acrosin and possibly representing fraction of acrosomal matrix.     

Failure of intramuscular antivenom in Red‐back spider envenoming

Four cases of Red‐back spider envenoming are reported in which there was minimal response to intramuscular antivenom. Intravenous antivenom was then administered in each case with almost complete resolution of symptoms. All cases were followed up to confirm the effect of treatment. This failure of intramuscular Red‐back antivenom raises the question of its efficacy. There has been no controlled trial to prove that intramuscular Red‐back antivenom is effective and animal work with other antivenoms has demonstrated the intramuscular formulation to have delayed and incomplete effects. Controlled studies should be undertaken to establish the effectiveness of intravenous and intramuscular Red‐back antivenom.     

Oral function in patients wearing fixed prosthesis on osseointegrated implants in the maxilla: 3-year follow-up study

Seventeen consecutive selected patients rehabilitated by means of a full maxillary bridge on osseointegrated implants ad modem Brånemark were evaluated over a 3-yr period. Besides a subjective evaluation by means of a questionnaire an examination of the occlusal relationship, chewing force, chewing efficiency and interocclusal threshold level was performed before, immediately after, 3–6 months after, and finally 3 yr after bridge installation. All subjects were very pleased with the oral rehabilitation. The chewing force and the chewing efficiency development increased over time, while the threshold level for interocclusal detection remained unchanged. The clinical dysfunction index according to Helkimo indicated that there was no marked change in signs of dysfunction of the patients' masticatory systems during the observation period. From the present longitudinal investigation one can conclude that the replacement of a full maxillary denture with a fixed prosthesis on osseointegrated implants, facing a natural dentition or an osseointegrated implant supported bridge in the opposite jaw, leads to a progressive increase of chewing efficiency and chewing force, and a constant subjective improvement of jaw function, while no masticatory dysfunction seems to occur during the observation period.     

Development of attraction to estrous females in male dogs

In simultaneous choice tests male beagles were allowed to visit a caged female in estrus, or caged, spayed female not in estrus. Males were tested periodically from 1-3 to 22-24 months of age. The 3 subject groups were normal males (Group N), males castrated 4-7 days postpartum and injected with testosterone propionate (TP) until they were 3 months old (Group TPTC), and males castrated 4-7 days but given no hormone treatment, i.e., untreated castrates (Group UC). A statistically reliable preference for visiting the estrous rather than the nonestrous female first appeared in N males at 4-6 months, in TPTC males at 1-3 months, and in UC males at 10-12 months. In N males attraction to the estrous female (measured by time spent visiting her) increased progressively from 4-6 to 16-18 months. In the same period concentration of plasma testosterone rapidly increased, reached a peak at 10-12 months, and then declined. UC males exhibited no significant increase in attraction to the estrous female from 10-12 months (when a preference first appeared) to 22-24 months. They then received 10 injections of TP after which their visiting time to the estrous female was equal to that of N males. TPTC males exhibited a precocious preference for the estrous female at 1-3 months, while they were receiving TP, and there was no decrease in strength of attraction in the following 9 months during which time no hormone was administered. Between 10-12 and 13-15 months, still without exogenous androgen, visiting to the estrous female began to increase and continued to do so until 19-21 months.     

Infrared-spectrometric determination of D2O in biological fluids

The determination of D₂O in biological fluids by means of infrared spectrometry was reinvestigated. When the temperature of a solution, containing D₂O in the range from natural abundance to 5 ml·1^–1 increases, its absorbance decreases and the wavenumber of maximum absorption shifts to a higher value. Both changes are linearly related to the change in temperature. Storage for 17 d in either glass or polyethylene tubes does not affect the D₂O concentration. Purification of biological fluids by vacuum-sublimation removes all substances which also absorb at the O-D vibration band and the recovery of D₂O from plasma and urine is complete. The partition ratio of D₂O between plasma water and red cell water equals unity, and the same holds for plasma water and urine water over a wide range of urine flows and osmolalities. The arterial and urinary disappearance curves of D₂O, measured over several days, both permit the calculation of the total amount of body water (V ^bw), the daily water turn-over (F) and the half-time of water in the body (t _1/2), but the data derived from arterial disappearance curves are more precise. In 16 male mongrel dogs (25–32 kg body mass) the following results were obtained:V ^bw=626±28 ml·kg^–1,F=12.0±3.2% andt _1/2=6.21±1.78 d.     

Hypoxic pulmonary vasoconstriction is heterogeneously distributed in the prone dog

Hypoxic pulmonary vasoconstriction (HPV) is thought to protect gas exchange by decreasing perfusion to hypoxic regions. However, with global hypoxia, non-uniformity in HPV may cause over-perfusion to some regions, leading to high-altitude pulmonary edema. To quantify the spatial distribution of HPV and regional PO2 (PRO2) among small lung regions (approximately 2.0 cm3), five prone beagles (approximately 8.3 kg) were anesthetized and ventilated (PEEP approximately 2 cm H2O) with an F1O2 of 0.21, then 0.50, 0.18, 0.15, and 0.12 in random order. Regional blood perfusion (Q), ventilation (VA) and calculated PRO2 were obtained using iv infusion of 15 microm and inhalation of 1 microm fluorescent microspheres. Lung pieces were clustered by their relative blood flow response to each F1O2. Clusters were shown to be spatially grouped within animals and across animals. Lung piece resistance increased as PRO2 decreased to 60-70 mmHg but dropped at PRO2's < 60mmHg. Regional ventilation changed little with hypoxia. HPV varied more in strength of response, rather than PRO2 response threshold. In initially homogeneous VA/Q lungs, we conclude that HPV response is heterogeneous and spatially clustered.     

The effect of pentobarbital anaesthesia upon the extracellular fluid volume in the dog,studied by continuous infusion and single injection methods

The effect of pentobarbital anaesthesia on the volume and ionic composition of the extracellular space was studied in adult male mongrel dogs with permanent catheters in aorta and pulmonary artery. The extracellular fluid volume (Q ^ec ) was determined with: a) methods based on equilibration of the indicator throughoutQ ^ec by continuous infusion; b) methods based on the assumption that after a single injection of indicator the plasma indicator concentration equals extracellular indicator concentration as long as the log plasma indicator concentration-time curve is linear; c) a single injection method based on a closed flow system model with a single inflow and a single outflow orifice. The measurements were made before and 30 and 90 min after induction of anaesthesia. Thirty minutes after induction of anaesthesiaQ ^ec as determined with the method sub a, had decreased by about 10% and remained so during the following 60 min. The values ofQ ^ec as calculated by the method sub c fairly agreed withQ ^ec as determined with the method sub a and also showed a decrease ofQ ^ec during pentobarbital anaesthesia. The procedures sub b overestimatedQ ^ec and yielded a seemingly higherQ ^ec during anaesthesia, because the boundary conditions for these procedures do not apply. The haemoglobin concentration decreased by about 10% and the lactate concentration by about 50%. The phosphate concentration increased by about 25% while the other electrolyte concentrations (Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl^–, HCO ₃ ^– ) did not change. A respiratory acidosis developed during the first 30 min and almost disappeared in the following 60 min. Possible explanations for the pentobarbital-induced concentration ofQ ^ec are discussed.     

深低温体外循环对犬趾蹼微循环指标的研究

本研究表明,深低温体外循环时,犬趾蹼微循环发生的变化与温度有关。平均动脉压(MAP)的变化不能反映组织灌注的优劣情况。毛细血管内的血流速度与灌注流量的高低有关。