Staple penetration and staple histological response for attaching an epimysial electrode onto the abdominal surface of the diaphragm using a laparoscopic approach

Background: Laparoscopic stapling was found to be a viable option for attaching epimysial electrodes onto the abdominal surface of the diaphragm. Stapling was preferable to suturing due to its simplicity and speed. Methods: Of the two staplers tested in this study, the Ethicon Endopath was preferred over the Autosuture Endo Hernia because the staples did not penetrate the diaphragm when an electrode tab thickness greater than 0.75 mm was used. Results: The thickness of the electrode tab was an important factor in determining staple penetration but large variation in penetration depth indicated that other factors may also play a role. An electrode tab thickness of 1.0–1.25 mm was suggested to minimize the risk of diaphragm perforation. Conclusions: The histological reaction to staples implanted up to 14 months was unremarkable, reflecting the safety of laparoscopic staples for permanently anchoring electrodes on the diaphragm. Received: 2 April 1996/Accepted: 12 June 1996     

Native HSV glycoprotein D subunit vaccine: analysis of in vitro T-cell activation and antigen presentation.

Native herpes simplex virus (HSV) glycoprotein D (ngD1) subunit vaccine, a potential human vaccine candidate, was examined to determine responsive murine lymphocyte populations in vitro. This vaccine preparation has been shown to protect against HSV challenge in mice and guinea pigs and to elicit humoral and cellular responses in rodents and primates. Immunized BALB/c mice were used in splenocyte lymphoproliferative studies to analyze the cellular response. After in vivo sensitization, the in vitro proliferative response observed appears to be resultant of Class II-restricted T-cell division in response to gD presented in the context of macrophage-expressed Ia.     

Gender differences in the effect of age on adrenergic neurotransmission in the heart.

In male rats, there is an age-associated decline in the capacity of cardiac sympathetic nerves to release norepinephrine. To investigate whether this phenomenon also occurs in female rats, we examined adrenergic neurochemical transmission in the hearts of female and male Fischer 344 rats. Rats aged 6, 12, and 24 months were employed. Hearts with the right cardiac sympathetic nerve intact were isolated and perfused with Krebs-Ringer solution. Stimulations were performed following the administration of cocaine or metanephrine separately and in combination or following the combination of cocaine, metanephrine, and yohimbine. Cocaine (1 microM) was used to block uptake 1, metanephrine (1 x 10(-5) M) to block uptake 2, and yohimbine (3 microM) to block alpha 2 receptor presynaptically. The nerve was stimulated with frequencies of 2, 6, and 12 Hz, and norepinephrine amount in the effluent was determined by high performance liquid chromatography/electrochemical detection methods. Neither norepinephrine release nor the effects of yohimbine, cocaine, or metanephrine were found to be affected in older female rats (24 month). This suggests that age-related changes in adrenergic neurochemical transmission in the heart of female rats differ from those seen in older male rats.     

Arsphenamine jaundice and the recognition of instrument-borne virus infection.

Soon after its introduction in 1910, intravenous arsphenamine treatment for syphilis was found to be complicated by jaundice. The underlying cause, unsterile syringes and needles, was eventually recognised in the early 1940s, mainly through the efforts of British Army investigators. The infection most often transmitted was probably hepatitis B virus (HBV), but the high mortality in a few of the outbreaks of arsphenamine jaundice suggests that variants of HBV, or other hepatitis viruses, were sometimes involved. Fifty years later, at a time when there are estimated to be over three hundred million carriers of HBV in the world and probably at least as many hepatitis C virus carriers, and when the World Health Organisation estimates that there have been 17 million infections with human immunodeficiency virus, the lessons learnt around 1945 about the need to use sterile instruments and needles for all injections and venepunctures remain highly pertinent.     

Effects of short-duration transients on cardiac rhythm

Cardiac stimulation thresholds of short-duration large-amplitude electrical transients were studied. An isolated rabbit heart model was used and transients were applied directly to the heart through electrodes of 1 mm² and 1 cm² surface area. A variety of oscillatory waveforms and pulse configurations were studied and indicated that, for transients shorter than 100 μs, stimulation thresholds approach a constant charge-transfer density of 3·4 μC cm⁻².     

Electrical properties of implant encapsulation tissue

The purpose of this study was to determine the electrical properties of the encapsulation tissue that surrounds electrodes chronically implanted in the body. Two four-electrode arrays, fabricated from either epoxy or silicone rubber, were implanted in each of six adult cats for 82 to 156 days.In vivo measurements of tissue resistivity using the four-electrode technique indicated that formation of the encapsulation tissue resulted in a significant increase in the resistivity of the tissue around the arrays.In vitro measurements of tissue impedance using a four-electrode cell indicated that the resistivity of the encapsulation tissue was a function of the tissue morphology. The tight layers of fibroblasts and collagen that formed around the silicone rubber arrays had a resistivity of 627±108 Ω-cm (mean ± SD; n=6), which was independent of frequency from 10 Hz to 100 kHz, and was significantly larger than the resistivity of the epoxy encapsulation tissue at all frequencies between 20 Hz and 100 kHz. The combination of macrophages, foreign body giant cells, loose collagen, and fibroblasts that formed around the epoxy arrays had a frequency-dependent resistivity that decreased from 454±123 Ω-cm (n=5) to 193±98 Ω-cm between 10 Hz and 1 kHz, and was independent of frequency between 1 kHz and 100 kHz, with a mean value of 195 ±88 Ω-cm. The results indicate that the resistivity of the encapsulation tissue is sufficient to alter the shape and magnitude of the electric field generated by chronically implanted electrodes.     

Semi-automated analysis of manually reconstructed tracks of progressively motile human spermatozoa

Several alternative algorithms for computer-assisted derivationof measurements of movement characteristics from manually reconstructedtracks of progressively motile human spermatozoa were compared.Fifty tracks were reconstructed at 30 Hz from video recordingsand analysed using traditional manual methods and by four combinationsof computer algo rithms. The best algorithm set was identified(‘Video-mot.mdpt’) and the values for the curvilinear,average path and linear velocities (V_CVL, V_AVE and V_LIN respectively),the amplitude of lateral displacement of the sperm head aboutthe axis of progression (A_H) and the number of times the spermhead crossed the average path (the ‘beat/cross frequency’,BXF) obtained using it were compared to those obtained by manualanalysis. There was a considerable time saving when the computer-assistedmethod was used and the values it gave for the various movementcharacteristics showed good correspondence with those obtainedmanually. In addition, repeated data entry and analysis wasfound to be highly reproducible. When the tracks were re-plottedat 6 Hz (as used by the multiple-exposure photomicrography methodfor sperm motility analysis) insufficient information remainedin the tracks for reliable determination of anything other thanV_LIN We conclude that the Videomot.mdpt program provides reliablevalues for the movement characteristics of progressively motilehuman spermatozoa, and believe it will be of great value inthe validation of commercial systems providing automated spermmovement analysis and in laboratories which do not have accessto such costly equipment.