Studies on the role of prostaglandins in the regulation of retinal blood flow

Prostaglandin E₁ was injected close to retinal arterioles by iontophoresis. Vasodilatation apparently similar to that caused by hypercapnia or hypoxia was observed. Inhibitors of prostaglandin synthetase were injected into the circulation. There was a reversible inhibition of the retinal vasodilation normally induced by hypercapnia. It is concluded that prostaglandin E₁ satisfies two criteria for a candidate for a mediator of hypercapnia-induced arteriolar dilatation. The effect of hypoxia appears more complicated.     

Possibility of passive transfer of cold urticaria to guinea pigs

Serum from one out of six patients with idiopathic acquired cold urticaria produced a short lived edematous reaction in the pinna of guinea pigs 24 hours after intradermal injection of the patient's serum and subsequent cold challenge. No relationship was observed between the transfer activity and IgE titer or atopic status.     

Possibility of using guinea pigs for studying the carcinogenic activity of some endogenous substances

The tryptophan metabolites 3-indolylacrylic acid and 2-aminoacetophenone, whose carcinogenic activity has been demonstrated by experiments on inbred mice, were injected into noninbred guinea pigs. Both substances induced tumors in the animals of the exprimental groups earlier than in the control and the tumors differed significantly in their morphology from those in animals of the control groups, evidence that both compounds have a carcinogenic effect. The results indicate that guinea pigs can be used to study the carcinogenic activity of weak carcinogens of the endogenous class.Experimental Animals Division, Oncologic Scientific Center, Academy of medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR L. M. Shabad.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 8, pp. 200–202, August, 1977.     

Cellular, Histomorphologic, and Clinical Characteristics of a New Octyl-2-Cyanoacrylate Skin Adhesive

Short-chained cyanoacrylates have been used for many years for topical skin closure. Toxic effects in cell culture of a new long-chained octyl-2-cyanoacrylate tissue adhesive are compared with those of short-chained ethyl-2- and butyl-2-cyanoacrylates. Two cellular tests were used: the agar overlay test and the MTT test. An in vitro test using copper plates coated with the three types of cyanoacrylates serves for evaluating the stability of polymerized skin adhesives. Bilateral neck skin incisions in Goettingen miniature pigs were glued on one side with Dermabond. On the other side, conventional sutures were applied. After the pigs were killed, the resulting skin samples were tested for the tensile strength of their wound stability. Samples of pig dermis were exemplarily and histomorphologically characterized. A clinical examination after submandibular lymph node dissection should examine the application in humans. Cell culture tests were used to show the toxic effects of the three cyanoacrylates. In a copper test, octyl-2-cyanoacrylate was more stabile than ethyl- and butyl-cyanoacrylates. Breaking strength was 30% lower 28 days after operation with the new product than with sutures. In electron microscopy, octyl-2-cyanoacrylate showed no disadvantages with regard to tissue regeneration and no histotoxicity. For plastic surgery, this new topical skin adhesive is a real alternative with attractive results, as compared with conventional suture.     

Methicillin-resistant Staphylococcus aureus in pig farming

We conducted a study among a group of 26 regional pig farmers to determine the methicillin-resistant Staphylococcus aureus prevalence rate and found it was >760 times greater than the rate of patients admitted to Dutch hospitals. While spa-type t108 is apparently a more widespread clone among pig farmers and their environment, we did find other spa-types.     

Comparative Ototoxicity of Dibekacin and Netilmicin in Guinea Pigs

Abstract: The cochleo- and vestibulotoxicity of dibekacin and netilmicin were compared in a guinea pig model. Both aminoglycosides were administered subcutaneously for 21 days at the dose level of 150 mg/kg/day. Control animals were injected with saline. Dibekacin-treated animals showed a significant (P<0.05) increase in the thresholds of the Preyer pinna reflex and the VIIIth nerve compound action potential in response to sound click stimulation. Moreover, a deterioration of the electrophysiologic auditory response and an almost complete suppression of the post-rotatory nystagmus were detected. In contrast, netilmicin did not induce any significant change in auditory and vestibular functions as compared to the control group. Our results demonstrated that netilmicin was devoid of ototoxicity in the guinea pig, while dibekacin provoked mild cochlear and severe vestibulotoxicity.     

Effect of lanthanum ions on the amplitude distributions of miniature endplate potentials and on synaptic vesicles in frog neuromuscular junctions

Miniature endplate potential (MEPP) amplitude distributions, MEPP frequencies and percentages of small MEPPs were determined as well as synaptic vesicle diameters and numbers in the frog neuromuscular junction during La3+ treatment. MEPP frequencies initially increased by two orders of magnitude and then fell to very low values. La3+ treatment had an initial postsynaptic effect making the MEPPs larger. Prolonged treatment had a variable effect on MEPP amplitudes. There were considerable variations in MEPP frequencies in adjacent junctions so single junctions on edge muscle fibers were recorded for the duration of many experiments and later identified in the electron microscope. Therefore, the physiological and morphological conditions of a given identified junction could be compared. There was a loss of synaptic vesicles and no change in mean diameter during depletion. During high MEPP frequencies infoldings occurred on the axolemma and these disappeared when MEPP frequencies decreased towards the end of the La3+ treatment. After 3-4 h of La3+ treatment, the overall frequency of MEPPs dropped and many were composed of a small class of MEPPs. It is suggested that the morphological correlate of small MEPPs, as well as the classical bell-MEPPs is likely to be synaptic vesicles.     

Contact sensitivity to acrylate compounds in guinea pigs

As reports of contact dermatitis in humans due to acrylate compounds have increased considerably in recent years, it was decided to investigate the ability of these chemicals to evoke contact sensitivity skin reactions in guinea pigs. 21 different acrylate and methacrylate compounds were scanned for their ability to induce contact sensitivity, using 5 different sensitization protocols. Contact reactions of varying intensities were produced to all the mono-, di- and triacrylates tested. However, it was not possible to sensitize guinea pigs to any methacrylates. It would appear that guinea pigs cannot be contact sensitized to acrylate chemicals that are substituted on carbon 2.     

Bursts of miniature end-plate potentials can be released from localized regions of the frog motor nerve terminal

We examined spontaneous transmitter release by simultaneously recording from end-plates with both an intracellular electrode and a focal extracellular electrode. In normal Ringer's solution the focal releases appear to be a near random portion of the pooled output. But in elevated [Sr²⁺]_out bursts of miniature end-plate potentials (m.e.p.p.s.) occur, and these can be localized at a portion of the presynaptic terminal. The bursts are not artifacts caused by the focal recording technique. In some conditions, sections of the nerve terminal can exhibit an enhanced probability of quantal release that persists for seconds.We occasionally observe extracellular events that must be generated by m.e.p.p.s. in adjacent fibers.     

豚鼠胎仔肾脏巨细胞病毒感染的实验研究

目的　探讨豚鼠胎仔肾脏巨细胞病毒感染与妊娠结局的关系。方法　随机选择孕早期豚鼠 2 0只 ,腹腔接种巨细胞病毒 ,观察其妊娠结局 ,分娩后 2 4h内处死新生豚鼠。用地高辛标记的巨细胞病毒晚期mRNA三相探针进行原位杂交 ,检测豚鼠胎仔肾脏内巨细胞病毒负荷量及分布情况。结果　 2 0只母豚鼠共妊娠 6 3只胎仔 ,其中足月活产并存活到 2 4h以上的胎仔 4 2只 ,流产等异常胎仔 2 1只。原位杂交检测正常胎仔巨细胞病毒感染率 7 1% (3/ 4 2 )、平均吸光度 (A)为 0 10 5±0 0 5 2 ,异常胎仔巨细胞病毒感染率 2 8 6 % (6 / 2 1)、平均A为 0 15 8± 0 0 4 7,两者平均A比较 ,差异有显著性 (P <0 0 5 )。杂交阳性信号主要分布在肾小管和集合管上皮细胞。结论　巨细胞病毒晚期mRNA主要在肾小管和集合管上皮细胞中表达 ,其表达水平与异常妊娠结局相关。