Angiographic studies of quinton—scribner arteriovenous cannulae

An analysis of 86 angiographic studies of Quinton–Scribner shunts has shown that these may be very useful in determining the cause and helping in the management of poorly functioning cannulae in patients on regular haemodialysis treatment.     

Effect of cannulae in the ampulla of the oviduct and in the tubo-uterine junction on reproductive phenomena in sheep

Permanent cannulation systems designed for injecting spermatozoa or for collecting eggs and fluids at the tubo-uterine junction and at the ampulla near its junction with the isthmus of the oviduct are described. In a preliminary experiment three ewes bilaterally cannulated in the tubouterine junction had spermatozoa injected through the cannulae and 4 of 8 eggs recovered were fertilized. Six more ewes were bilaterally cannulated. They continued to cycle and few complications were experienced. But cannulation appeared to reduce superovulatory response to exogenous gonadotropins. This also occurred in a confirmatory study with 16 rabbits in which super-ovulated controls averaged 25.6 ovulations versus 8.6 in those with cannulae. When cannulae were installed near the ampullar-isthmic junction no eggs were recovered surgically from 4 controls. Thus, these cannulae appeared to interfere with ampullary transport of eggs.Blood plasma concentrations of LH and progesterone were not affected by cannulae. As cycle length also was normal it appeared that these devices were not luteolytic.The cannulae were still functioning in the animals euthanized more than six months after installation. Thus, once installed, they appear to offer a non-surgical means of examining several aspects of reproductive function associated with fertilization. The observations on altered egg transport and ovarian response to gonadotropins may be of significance in certain cases of infertility.     

A numerical study on the effect of side hole number and arrangement in venous cannulae

Insertion of cannulae into vessels may apply non-physiological load and stress on blood cells, such that adenosine diphosphate may increase and result in hemolysis. Authors used the computational method to simulate the blood flow inside of the cannula. We limited the research to within the drainage cannulae. Nine different cannulae categorized by the number of side holes of 4, 12, and 20, and also categorized by the array type as staggered array, in-line array, and alternative in-line array were studied and compared to the cannulae with no side holes by using computational fluid dynamics. We evaluated the flow rate, the wall shear stress, and the shear rate, and compared them with one another to estimate the effect of the side holes. The flow rate is not proportional to the number of the side holes. However, larger number of side holes can reduce the mean shear rate.     

An in vitro fluid dynamic study of pediatric cannulae: the value of animal studies to predict human flow

A challenge to the development of pediatric ventricular assist devices (PVADs) is the use of the aortic cannulae attached to the devices. Cannulae used for pediatric application have small diameters and large pressure drops. Furthermore, during the development of the 12cc Penn State pediatric PVAD, particle image velocimetry (PIV) illustrated that hematocrit levels, through changes in blood viscoelasticity, affected the fluid dynamics. The objective of this study is to compare the fluid dynamics of a pediatric viscoelastic blood analog and a goat viscoelastic blood analog within the PVAD aortic cannula. Two acrylic models were manufactured to model the aortic cannula (6 mm and 8 mm diameters). PIV data was collected to examine the flow at the outlet of the VAD and in the aortic cannula at heart rates of 50 and 75 beats per minute (bpm). Three planes of data were taken, one at the centerline and two 1.5 mm above and below the centerline. Three more planes of data were taken orthogonal to the original planes. While a 75 bpm heart rate was used to represent normal operating conditions, a 50 bpm heart rate represented use of the PVAD during weaning. At 75 bpm, differences were evident between the two different fluids and the two models. Separation zones developed in the plane below the centerline for the higher hematocrit pediatric blood analog. This study raises question to the usefulness of animal testing results in regard to how well they predict the outcome of pediatric patients.     

Pyrodictium cannulae enter the periplasmic space but do not enter the cytoplasm,as revealed by cryo-electron tomography

The hyperthermophilic archaeon Pyrodictium grows in the form of a macroscopically visible network. It consists of cells entrapped in an extracellular matrix of hollow tubules, the "cannulae." Here, we present the three-dimensional structure of a single cell in conjunction with two extracellular cannulae, as determined by cryo-electron microscopy. To achieve this, the information from two independent tilt series of the same specimen was combined, with the specimen rotated in the second series. In the three-dimensional tomographic reconstruction, we were able to trace the two cannulae in their full length, in particular, also inside the cell. One cannula enters the periplasmic space, while the other cannula contacts the surface of the cell, the S-layer. This indicates that the cannulae interconnect individual cells with each other on the level of their periplasmic space; we do not, however, have evidence that they enter the cytoplasm of the cells. The implications of these data for possible functions of the cannulae are discussed.     

Seasonal changes in the in-vivo activity of the luteinizing hormone-releasing hormone (LHRH) neural apparatus of male rabbits monitored with push-pull cannulae

Intact sexually mature New Zealand White male rabbits, raised under natural lighting and temperature conditions, were isolated and housed in air-conditioned quarters, in a 12-h light:12-h dark cycle. Push-pull cannulae were implanted towards the tuberal region of the hypothalamus, and animals were perfused with modified Krebs'-Ringer phosphate medium for an average period of 4 h. Most rabbits were repetitively perfused over an average period of 3.7 months. Perfusions were grouped into seasonal periods of about 40 or 80 days through the entire 1-year cycle: (A) 23 November to 31 December (winter solstice period: N = 6), (B) 1 January to 23 March (winter: N = 10), (C) 24 March to 13 June (spring: N = 9), (D) 14 June to 23 July (summer solstice period: N = 23), (E) 24 July to 13 October (late summer-early fall: N = 7) and (F) 14 October to 22 November (fall: N = 4). Maximal and minimal values of mean release, mean amplitude and mean frequency from every animal in each block were obtained. In the summer solstice group (D), maximal mean (+/- s.e.) LHRH release levels were significantly greater (14.42 +/- 6.62 pg/10 min) than for all groups (A, 0.76 +/- 0.27; B, 1.59 +/- 0.39; C, 1.34 +/- 0.22; E, 1.33 +/- 0.33; and F, 1.18 +/- 0.11) while during the winter solstice period (A), minimal mean LHRH release levels (0.48 +/- 0.04 pg/10 min) were significantly lower than in all other groups (B, 1.43 +/- 0.41; C, 0.96 +/- 0.11; D, 7.25 +/- 4.12; E, 1.18 +/- 0.37; and F, 1.18 +/- 0.11). Maximal values were highest during the summer solstice period while the minimal values were lowest during the winter solstice period. The amplitude and frequency of the LHRH pulses showed changes similar to those observed with the mean LHRH release. For 1 year, an estimated left testis weight was measured in 4-7 rabbits every 2-5 weeks. The percentage estimated testis weight peaked in early August and reached minimal levels during the winter months. These data demonstrate that the rabbit LHRH neural apparatus is very sensitive to seasonal influences although animals remained in a fixed photoperiod during the entire duration of the experiment.     

The metabolism of dopamine in rat caudate nucleus can be increased by in vivo “dialysis” perfusion cannulae

The development of dialysis cannula techniques coupled with high performance liquid chromatography and electrochemical detection (HPLC-EC) has provided a means to continuously sample extracellular fluid from deep brain structures $\text{in vivo}$. The present studies show that with HPLC-EC analysis of the acid metabolites of dopamine (DA) and 5-hydroxytryptamine (5-HT) in samples from dialysis cannulae implanted in the caudate nucleus of anaesthetized rats, it is possible to determine the time course of the response of dopamine- and 5-HT containing neurones to administration of monoamine oxidase inhibitors and haloperidol. The tissue concentrations of the DA and 5-HT metabolites were also determined at the conclusion of each individual experiment in both the caudate nucleus containing a cannula and in that without a cannula. In perfusion experiments where no drug was administered the content of the DA metabolites, but not that of the 5-HT metabolite, were significantly elevated in the caudate nucleus containing the cannula as compared with the contralateral tissue. These increases occurred whether the cannula was perfused or not, suggesting that the presence of the cannula may have been causing a lesion which altered the activity of the DA neurones. These results emphasize the importance of tissue analysis in conjunction with the dialysis experiments, especially where perfusion sample contents of the monoamine metabolites are being measured as a reflection of the effects of behavioural manipulation or drug treatment on endogenous neuronal activity.     

Release of luteinizing hormone-releasing hormone (LHRH) and neuroactive substances in unanesthetized animals as estimated with push-pull cannulae (PPC)

In this report, we have reviewed recent information gathered by probing with a push-pull cannula (PPC) the in vivo activity of the suprachiasmatic nucleus (SCN), hypothalamus, and anterior pituitary gland of freely moving animals. In male and female rats, probing of the SCN with the PPC revealed distinct oscillatory patterns of 5-hydroxy indole-acetic acid (5-HIAA) output very much dependent on the position of the cannula. In males, it was also possible to demonstrate, for the first time, in vivo output of immunoreactive vasopressin (VP) most likely from the SCN. Interestingly, the output of VP was stimulated by local activation of probable 5-hydroxytryptamine (5-HT) terminals with 5-hydroxytryptophan (5-HTP), a precursor of 5-HT synthesis. Probing the hypothalamus of rats and rabbits revealed that the in vivo release of luteinizing hormone-releasing hormone (LHRH) (frequency and amplitude of the LHRH signal) can be altered by administration of estrogen to ovariectomized rats; in both species, progesterone stimulated the amplitude of the LHRH signal, but only when this steroid was infused in pulses--the physiological mode of circulating progesterone in the rat. Further, in male rabbits, pulses of progesterone did not stimulate LHRH release. Last, probing the anterior pituitary with the PPC revealed that a series of push-pull perfusions could be performed in the same animal under different experimental conditions for nearly 60 days of experimentation. It also resolved the apparent paradox that after castration, decreased instead of increased activity of the neural LHRH apparatus was noticed when the PPC was positioned in the hypothalamus. Moving the PPC to the anterior pituitary revealed that castration was accompanied by an increase in the amplitude and frequency of the LHRH signals arriving in the anterior pituitary of castrated male rats. This mode of operation of the LHRH pulse generator is clearly compatible with the mode of luteinizing hormone (LH) release in gonadectomized animals. Finally, based on these results, a hypothetical model of the operation of the LHRH pulse generator has been proposed.     

Antibiotics in the treatment of wounds in the victims of the earthquake in the Armenian SSR

Purulent wounds in 88 victims of the Armenian earthquake with the syndrome of long-term squeezing were examined microbiologically and the experience with using antimicrobial drugs for their treatment was analyzed. In all the cases microbial associations were detected, coliform and nonfermenting gram-negative bacilli, enterococci, anaerobes and yeast-like fungi being isolated from 80, 20, 15 and 25 per cent of the patients respectively. 130 bacterial strains were studied in detail. 80 to 100 per cent of the bacterial isolates were resistant to the antibiotics routinely used in surgical practice, i.e. benzylpenicillin, tetracycline, levomycetin, kanamycin, cephalothin and cefazolin and highly sensitive to new antimicrobial drugs belonging to ureidopenicillins (mezlocillin), quinolones (ciprofloxacin) and cephalosporins of the 3rd generation (cefoperazone and ceftazidime). Retrospective estimation of the antibiotic therapy revealed its inadequacy in 55.7 per cent of the patients for the most part because of the isolates resistance. The 19 variants of the antibiotic use prescribed by the physicians mainly included penicillins, aminoglycosides and their combinations (in 67.2 per cent of the cases). The use of the highly efficient drugs of the groups of ureidopenicillins and quinolones was extremely rare which was likely due to lacking of information on the drugs.     

Histogenesis of the taste buds of the vallate papilla in the in the rat in the postnatal stages of development

The developing taste buds of vallate papillae were studied with electron microscope in rats during the first 7 days after birth. Two types of cells--light and dark--are identified in the taste buds of a one day old animal. The apical parts of dark cells are characterized by numerous dark granules. A distinguishing feature of light cells is the presence of synaptic contacts with afferent intragemmal nerves. On the 4th day of development on the top of the apical parts of the cell, a microvillar apparatus is seen to form, which does not yet communicate with the oral cavity. On the 7th day, basal cells appear in the taste buds. Some of these cells are seen mitotically dividing. The differentiated microvillar apparatus now communicates with oral cavity. The structure of the taste buds is getting similar to that in the adults. The structural and functional peculiarities of the developing taste buds are discussed in association with the period of ontogenesis under consideration.     

Changes in the size of the nucleoli of the Purkinje cells in the canine cerebellum in the postresuscitation period

The changes in the size of Purkinje cell (PC) nucleolus in the lateral and medial cerebellum zones were studied in dogs with different degree of neurologic status recovery after clinical death of various etiology and duration. PC always possess one nucleolus in the control and experimental groups. In the case of complete neurologic status recovery of animals the area of PC nucleolus increases in both zones studied, irrespective of the cause of clinical death. In the case of neurologic disorders the increase in PC nucleolus area is clearly expressed only in the medial zone of the cerebellum, being insignificant in the lateral zone. It is suggested that adaptive characteristics of PC are distinct in the two compared zones, which leads to greater PC vulnerability in the lateral zone during deep hypoxia.     

Frequency of the stages in the cycle of the seminiferous epithelium in the rat

This study determined the optimum number of tubules to be counted per testis cross section, and the number of animals per treatment group, when changes in stage frequencies in the cycle of the seminiferous epithelium are criteria for assessing effects of treatment on spermatogenesis. A data base of 9,672 observed and staged tubules was collected from testicular cross sections of 15 Sprague-Dawley rats. A significant variation between animals was found for the frequencies of Stages I, II, IV, VI, VIII, and XIII. Computer simulation was used to randomly select different combinations of animal and tubule numbers from the observed data. Stage frequency means from each simulation experiment were compared statistically to observed mean frequencies. A model that used data from all 14 stages was analyzed. The following conclusions were made: a) a minimum of 200 tubule cross sections/testis is recommended for estimating stage frequencies; b) for a fixed number of tubules scored, the number of animals sampled is more important than the number of tubules per animal in reducing variance; c) to detect a difference of 2 standard deviations from the mean with a 2% error rate and examining 200 tubules/testis, at least 12 animals must be used per group when assessing all 14 stages; d) when individual stages are examined using 10 animals per group, only Stage VII has 80% or greater power of test (alpha = 0.05) to detect a frequency difference; e) pooling stages into 3-4 groups is recommended to improve the power of detecting a treatment difference.