Effect of some additives on the biostability of a poly(etherurethane) elastomer

Four materials based on a single poly-(etherurethane) (PEU) prepared from MDI and PTMEG but differing in additives were studied in the cage implant system. The two additives studied were Santowhite powder at the 1% level and Methacrol 2138F 5%. Methacrol 2138F appeared to be immiscible with the base PEU and was dispersed in discrete domains about 0.5-micron in size. The retrieved PEU specimens were also cleaned and examined in the optical and scanning electron microscopes, and the size and density of adherent foreign body giant cells (FBGCs) were measured at implantation times up to 10 weeks. Methacrol 2138F had no effect on the density, coverage or size distribution of adherent FBGCs, but leaching of Methacrol 2138F was considered to be responsible for extensive pitting of the PEU surface. On the other hand, Santowhite powder appeared to inhibit formation of FBGCs, and while surface cracking and flaking were observed as early as 3 weeks postimplantation on some PEUs, the Santowhite powder effectively inhibited surface cracking and flaking up to the longest implantation time studied.

[Effect of acupuncture on intestinal motion and sero-enzyme activity in perioperation]

The authors study on abdominal surgical patients (39 cases) who were randomly divided into the acupuncture and control group. In the acupuncture group, the needle inserted into Zusanli (St.36) and Sanyinjiao (Sp. 6) points at 12-24 h after operation and observed the time of the first excretion through anus. Sero-enzyme activity of GPT, GOT and gamma-GT determined before operation and at 1, 3, 5, 7 days after operation. The results showed that the time of excretion in the acupuncture group (57.78 +/- 23.94 h) was obviously faster than the control one (86.14 +/- 20.43 h), P less than 0.001). It suggested that acupuncture has the effect of promoting intestinal motion. After operation sero-enzyme activity was raised 2-3 times than before. It showed that the surgical trauma directly or indirectly impair cells to release enzyme into blood, but the time of reversing to normal level of sero-enzyme activity in the acupuncture group was obviously faster. There is possibility that acupuncture has the effect of regulating reactivity of organism on trauma and promoting the repair of damaged cell.

The effects of the combination of phentolamine and vasopressin on hepatic and systemic hemodynamics in cirrhotic portal hypertensive dog model

The experimental study was aimed at elucidating the effects of phentolamine and vasopressin used separately or in combination on hepatic and systemic hemodynamics in cirrhotic portal hypertensive dogs. The results showed that either of the two drugs used separately could lead to reduction in portal venous pressure and could also influence systemic hemodynamics or lower hepatic blood flow. When phentolamine in combination with vasopressin was administered, no side-effect could be found on hepatic and systemic hemodynamics, suggesting that the drugs used in combination could efficaciously decrease portal hypertension and counteract their respective side-effect. This combination therapy will be useful in treating bleeding from esophageal variceal rupture in cirrhotic patients with portal hypertension.

Effect of drying on regenerating rat sciatic nerve

To study the effects of drying on regeneration, crush lesions were made on the sciatic nerve of 38 rats and the injured area was then air-dried for various periods of time (0-60 min). The regeneration distance of sensory nerve fibres was measured by the pinch reflex test three or six days later. Regeneration was significantly impaired by drying the nerve for 30 or 60 min, but shorter periods (10 min) also seemed to affect axonal outgrowth. Regeneration distances were increased in nerves that were subjected to drying and then allowed to recover for a week (conditioning interval) before the nerve was crushed. The results show that drying of a peripheral nerve is detrimental to nerve regeneration, and we suggest that nerves should not be exposed to air for more than a few minutes during operation without irrigation.

Definition of a sequence, RYVVLPR, within laminin peptide F-9 that mediates metastatic fibrosarcoma cell adhesion and spreading

A synthetic peptide from the inner globule of the B1 chain of laminin, termed peptide F-9 (RYVVLPRPVCFEKGMNYTVR; residues 641-660), has been shown to have heparin-binding and cell adhesion-promoting activities for diverse cell types (Charonis et al., J. Cell. Biol., 107: 1253-1260, 1988). In this study, the metastatic murine fibrosarcoma cell line, UV-2237-MM, adhered and spread on surfaces coated with laminin and peptide F-9 in a concentration- and time-dependent fashion. Cells migrated toward laminin in Boyden microchemotaxis chambers but not toward peptide F-9. However, exogenous soluble peptide F-9 inhibited both the adhesion and migration of cells toward laminin. Polyclonal antibodies raised against peptide F-9 were capable of inhibiting laminin-mediated cell adhesion and migration. Peptide F-9 is located 265 residues from CDPGYIGSR, another sequence on the B1 chain of laminin which has been reported by others to promote cell adhesion (Graft et al., Cell, 48: 989-996, 1987). In contrast to peptide F-9, various control peptides including CDPGYIGSR did not promote the adhesion, spreading, or migration of the UV-2237-MM fibrosarcoma cells. In addition, neither exogenous peptide CDPGYIGSR nor antibodies raised against peptide CDPGYIGSR were capable of inhibiting laminin-mediated cell adhesion or migration. These results indicate that peptide F-9, but not peptide CDPGYIGSR, represents a major fibrosarcoma cell adhesion-promoting domain on intact laminin. A series of overlapping peptides were synthesized which contained various portions of the parent peptide F-9. The use of these peptides in cell adhesion assays demonstrated that the sequence RYVVLPR from the amino terminus of peptide F-9 was essential for cell adhesion-promoting activity.

[Study on change in zinc concentration for diabetic cataractous lenses in rats by means of XIXA]

The SD rats were injected with streptozotocin to induce diabetic cataract. Element Zn as well as K, Ca, Mn, Fe, Cu, Pb, Se, etc. in the eye lenses was determined by means of X-ray induced X-fluorescence analysis (XIXA). Compared to values for normal healthy rats, the concentration of Zn and Fe in the cataractous lenses increased, the concentration of K decreased, and that of the others did not change prominently. The change in Zn concentration was probably to meet the needs of the metabolic adjustment in the eye lenses, which would not be the reason for directly inducing diabetic cataract.

Cellular interactions with biomaterials: in vivo cracking of pre-stressed Pellethane 2363-80A

The phenomenon of stress cracking of Pellethane 2363-80A (PEU) was investigated using the cage implant system. A cytotoxic polyvinylchloride (PVC) and a silicone rubber containing an anti-inflammatory steroid were used to create inflammatory environments in which the biostability of the pre-stressed PEU was tested. These coimplants provided alternative in vivo environments to study in vivo polymer interactions. The inflammatory responses to the implanted cages were monitored by analyzing the exudates aspirated from the cages at different implantation times over 21 days. The pre-stressed PEU specimens were retrieved after 5, 10, and 15 weeks postimplantation and examined by optical microscopy (OM) and scanning electron microscopy (SEM). The results support the conclusion that in vivo cracking of stressed (strained) Pellethane 80A is related to cell-polymer interactions. Severe cracking or rupture of the implanted PEU specimens was observed as early as 5 weeks postimplantation. Molecular chain degradation of the implanted specimens was evident from molecular weight measurements. Neither surface cracking nor degradation of macromolecules was found on the pre-stressed PEU specimens with the added cytotoxic PVC implanted over 15 weeks. No cracking was observed on the pre-stressed specimens in the presence of steroid silicone rubber, even after 10 weeks implantation.

[Experimental studies of specific neuro-chemotaxis in peripheral nerve regeneration in the rat]

In this paper are reported the results of a systematic study of chemotactic effect and other features of the regeneration of severed peripheral nerve in rat. The results revealed that (1) the proximal stumps of tibial and peroneal nerves tended to grow to their original distal stumps, (2) motor branch and sensory branch also showed preferential growth to the homojunctional patterns of nerve grafts, (3) using muscle and skin as targets, these not only attracted nerve growth, out also selectively attracted motor branch and sensory branch. Our results indicate that during rat peripheral nerve regeneration there exists neurotropism as evidenced by tissue specificity, topographic specificity, functional pattern specificity and target specificity. Based on these findings, the possible mechanism of neurochemotropism is discussed. Distance between the stumps, selective use of experimental chamber material and the clinical significance of this neurotropic research are also discussed.

[Establishment of hybridoma cell lines producing monoclonal antibodies against-p30 antigen]

BALB/c mice were immunized with the purified p30 antigen. SP2/0 myeloma cells and immune spleen cells were fused with 50% PEG (Sigma, MW 3,350-4,000). The cell fusion rate was 93.95%, and the antibody producing rate 21.01%. The technique of limiting dilution was used for cloning of the hybridoma cells. Two hybridoma cell lines E8 and G1 secreting McAb against p30 antigen were obtained. The number of chromosome of both E8 and G1 cell lines was 98.7 +/- 6.54 and 97.7 +/- 7.77, respectively. Results of the PAGE of the ascites generated by the hybridoma cell lines E8 and G1 showed a thick protein band at the gamma-region which was absent from the ascites generated by the SP 2/0 myeloma cells. The immunoglobulin of the McAb E8 and G1 belonged to IgG2 subclass. The results of the immunohistochemical method using the horseradish peroxidase conjugated antibody showed that both E8 and G1 McAb only reacted with epithelial cells of the normal human prostatic glands and their ducts, but did not cross-react with other thirty-four different kinds of normal human tissues. The results of inhibiting ELISA test showed that both E8 and G1 McAb were only inhibited by the human seminal plasma and p30, weakly inhibited by the adult male's urine, but were not inhibited by other eight different kinds of human body fluids and secretions as well as semen from eight different species of animals. It was concluded that McAb of E8 and G1 were organ and species specific.(ABSTRACT TRUNCATED AT 250 WORDS)

Neurotropism to tissue specificity in nerve regeneration. Experimental study on sciatic nerves of rat

Using the left sciatic nerves of 44 rats we studied neurotropism in nerve regeneration. The proximal and distal cut ends of the nerves were separately introduced into the ends of a specially designed silastic Y- or cross-shaped tube. Either the distal stump or a cut end of the Achilles tendon was inserted into the other ends of the tube, or was left empty. The distance between the tissue ends, nerve-to-nerve or nerve-to-tendon, was 4 mm. Four weeks later, neurofibers sprung out from the proximal stump and grew towards the distal nerve end instead of the tendon end or the vacant channel of the tube. This finding suggests that neurotropic factors may influence the direction of growth of the newly formed neurofibers. This paper discusses the mechanism of neurotropism, the effect of the distance between the cut ends of the nerve, and the choice of the silastic material.

[Phentolamine in cases of liver cirrhosis with bleeding from esophageal variceal rupture]

The aim of this study is at establishing cirrhotic portal hypertension with common bile duct ligation in 9 mongrel dogs to measure the plasma catecholamine level. On the basis of experimental study, phentolamine, the alpha-adrenoceptor antagonist, was used to treat 14 patients with liver cirrhosis complicating bleeding from esophageal variceal rupture. The results had been shown that the levels of noradrenaline (NE) in both portal and inferior caval vein were increased more significantly in the cirrhotic stage than in the precirrhotic stage. The mechanism of the NE elevation might be due to increased release from enhancement of sympathetic nervous activity. Our clinical data have also been demonstrated that the effect of phentolamine on the 12 cases of variceal hemorrhage is markedly efficacious with no longer bleeding. Only 2 patients had showed no good reaction neither to phentolamine nor to pituiterin, eventually died of liver failure. It is conceivable that phentolamine has the same efficacy in treatment of esophageal variceal bleeding as pituitrin. But less side effect than the latter.

[Neurotropism to tissue specificity in nerve regeneration: an experimental study on the sciatic nerves of the rat]

A study of neurotropism in nerve regeneration was carried out on 44 rats, using their left sciatic nerves severed to work up. The cut ends of proximal and distal stumps were separately introduced into amend of the specially designed silastic tube of Y- or cross-shape. Into the other ends of the tube were inserted either the end of the distal stump or a cut end of achilis tendon on the same side, or were left empty. The distance between the tissue ends, nerve-to-nerve or nerve-to-tendon, was 4 mm. Four weeks later, it was found in the specimens that the growth of neurofibers sprung out from the end of the proximal stump directed towards the distal nerve stump rather than towards the tendon end or the vacant limb of the tube. This fact strongly speaks for that there is some thing neurotropic factor, guiding the direction of growth of the newly formed neurofibers, a property of tissue specificity. The mechanism of neurotropism, the effect of the distance between the cut ends of the nerve and the choice of the silastic material were discussed.