A new 1.9-mu wavelength laser for neurosurgery.

The 1.9-mu wavelength component of a 1.9/1.06-mu two-wavelength laser with near-continuous wave properties was tested for its potential use in neurosurgery. The 1.9-mu wavelength has tissue-ablative capabilities, while the 1.06-mu wavelength (Nd:YAG) is suitable for achieving hemostasis. The advantages of the 1.9-mu wavelength over the CO2 laser include its ability to transmit through silica fiberoptic delivery systems and its deeper penetration in water (approximately 100 mu, a depth 10 times greater than for the CO2 laser), which is compatible with irrigation during ablation. To test the effectiveness of the laser, bilateral craniotomies were performed in anesthetized rats immobilized in a stereotactic frame. Under an operating microscope, lesions were made on the cortex by delivering the 1.9-mu laser beam through a 400-mu fiber at an average power of 1 W over a range of fluences. Subjective intraoperative observations were notable for minimal bleeding, absence of charring when the tissue was irrigated with a thin stream of saline, and uniform lesion formation. For comparison, lesions were generated with a commercially available continuous-wave CO2 laser at equivalent power and fluences. Histological specimens were divided into three groups based on the study after laser application: acute (30 minutes), subacute (48 hours), and chronic (14 days). The extent of thermal injury for the 1.9-mu laser in the acute lesions was quantitatively and histologically similar to that generated by the CO2 laser. Regions of injury extended approximately from the apex of the lesion, and crater depths generated by both lasers were similar (250 to 750 mu) in the range of fluences investigated (1.25 to 10 kJ/sq cm). Subacute and chronic histological specimens demonstrated inflammatory and repair responses that correlated with the acute injury regions in both the 1.9-mu and CO2 laser-treated specimens. This study demonstrates a neurosurgical potential for a new two-wavelength laser that ablates tissue effectively with limited thermal injury. The 1.9-mu laser is comparable to the widely used CO2 laser but offers several unique advantages, including the ability for delivery through a fiberoptic system and to irrigate tissue during use.

New titanium alloys for biomaterials: a study of mechanical and corrosion properties and cytotoxicity.

Three new titanium alloys with Zr, Nb, Ta, Pd and In as alloying elements were developed and compared with currently used implant metals, namely, pure Ti and Ti-6Al-4V alloy, in terms of mechanical and corrosion properties, and cytotoxicity. New alloys showed comparable mechanical properties with that of the Ti-6Al-4V alloy, but increased corrosion potential, somewhat decreased breakdown potential and increased corrosion rate. There were no significant differences in cell growth on the surface of the various metal specimens, indicating that the cells cannot differentiate between the passivated surfaces of the various Ti metals.

Photoselective vaporization of the prostate (GreenLight PV): lessons learnt after 3500 procedures.

The technical recommendations of an international group of experts on photoselective vaporization of the prostate (PVP; GreenLight PV) for benign prostatic hyperplasia are described. Their experience stems from the treatment of over 3500 patients at five centres in Europe and the United States. The objectives of this physician-based initiative are to optimize the results achieved with PVP by standardizing the procedure, as well as to recommend training requirements.

Preperitoneal prosthetic mesh hernioplasty during radical retropubic prostatectomy.

PURPOSE: The number of radical retropubic prostatectomies performed in the United States has increased during the last decade. There are 5 to 10% of candidates for radical retropubic prostatectomy who have a detectable inguinal hernia on physical examination. Furthermore, recent data suggest that there is an increased incidence of inguinal hernia after radical retropubic prostatectomy. We evaluated the role of simultaneous inguinal hernioplasty during radical prostatectomy. MATERIALS AND METHODS: During 575 radical prostatectomy procedures from June 1991 to June 1997, 70 hernioplasties were performed in 48 patients. Retrospective chart review was performed for all men who underwent simultaneous hernia repair. Mean patient age was 60.9 years (range 43 to 73). Polypropylene or polyester fiber prostheses were used for mesh hernioplasty. All repairs were performed using a preperitoneal approach during radical retropubic prostatectomy. RESULTS: There were 35 hernioplasties performed without and 35 with mesh. Mean postoperative followup was 24 months (range 6 to 66). Of the hernias 71% were indirect and 29% were direct. No recurrence was detected after mesh hernioplasty, whereas 5 hernias (14%) recurred in the nonmesh group. In this group 2 men (4%) also had de novo hernias on the contralateral side during followup. All recurrent hernias were diagnosed within 1 year of the initial operation. No patient had wound infection, persistent neuralgia or ischemic orchitis. CONCLUSIONS: Simultaneous repair of inguinal hernias during radical retropubic prostatectomy is effective and technically feasible. There is convenient access to the preperitoneal space during radical retropubic prostatectomy and hernia repair adds only 5 to 10 minutes of operative time. Mesh repair appears to offer optimized results compared to the nonmesh technique. Despite the use of prosthetic material, no complications were attributable to its application during these genitourinary procedures.

Transfer and expression of the lacZ gene in rat brain neurons mediated by herpes simplex virus mutants.

Three mutants of herpes simplex virus type 1 (HSV-1) were used to deliver and express the Escherichia coli lacZ gene in cells of the rat central nervous system. Because the lacZ gene was inserted in place of the genes encoding one of the immediate-early viral proteins ICP0 or ICP4 or the early viral protein thymidine kinase, these mutants were compromised or defective in their ability to replicate. All mutant vectors exhibited reduced pathogenesis in animals as compared to the wild type HSV-1 strain KOS. In all cases lacZ was under the control of immediate-early or early viral promoters that are active in the early phase of infection. Expression of beta-galactosidase was observed in cortical neurons following stereotactic inoculation of mutant viruses into adult rat brains; distinct patterns of expression were observed with each mutant vector. Injection of the ICP0 mutant in the frontal cortex and caudate nucleus resulted in beta-galactosidase expression in a substantial number of cells around the inoculation site and at some distance from it for 14 days, with maximum expression after 3 days. The ICP0 vector appeared to have reached the ipsilateral and contralateral cingulate cortex by retrograde transport. Following inoculations of the ICP4 and thymidine kinase vectors into the same brain regions, only a few cells in areas immediately adjacent to the injection track expressed beta-galactosidase and they did so for only a few days. These herpes virus-derived vectors provide a means for the in situ delivery and expression of specific genes in neurons in the central nervous system with little adverse effect on animals.