[Ocular complications of local anaesthesia in dentistry]. / Oculaire bijwerkingen van lokale anesthesie in de tandheelkunde.

An estimated 1 in 1,000 local anaesthetic injections in the maxilla or the mandible lead to unwanted effects on the ipsilateral eye. We have seen a case with diplopia and lateral rectus palsy following bimaxillary anaesthesia. A systematic literature review of reports on this type of complication resulted in a total of 144 documented cases published between 1936 and 2016. The most frequently reported symptoms included diplopia (72%), partial or full ophthalmoplegia (26%), ptosis (22%), mydriasis (18%), amaurosis (13%) and orbital pain (12%). This type of complication is best understood by pathophysiological hypotheses that include intra-arterial injection, intravenous injection, autonomic dysregulation, or deep injection and diffusion. If ocular symptoms appear after local intraoral anaesthesia, the patient should be reassured. In the case of diplopia, the eye should be covered with a gauze dressing, and the patient should be instructed about associated safety risks. If symptoms persist or when vision deteriorates, referral to an ophthalmologist is advisable.

The feasibility of local anesthesia for the surgical treatment of umbilical hernia: a systematic review of the literature.

BACKGROUND: Yearly approximately 4500 umbilical hernias are repaired in The Netherlands, mostly under general anesthesia. The use of local anesthesia has shown several advantages in groin hernia surgery. Local anesthesia might be useful in the treatment of umbilical hernia as well. However, convincing evidence is lacking. We have conducted a systematic review on safety, feasibility, and advantages of local anesthesia for umbilical hernia repair. METHODS: A systematic review was conducted according to the PRISMA guidelines. Outcome parameters were duration of surgery, surgical site infection, perioperative and postoperative complications, postoperative pain, hernia recurrence, time before discharge, and patient satisfaction. RESULTS: The systematic review resulted in nine included articles. Various anesthetic agents were used, varying from short acting to longer acting agents. There was no consensus regarding the injection technique and no conversions to general anesthesia were described. The most common postoperative complication was surgical site infection, with an overall percentage of 3.4%. There were no postoperative deaths and no allergic reactions described for local anesthesia. The hernia recurrence rate varied from 2 to 7.4%. Almost 90% of umbilical hernia patients treated with local anesthesia were discharged within 24 h, compared with 47% of patients treated with general anesthesia. The overall patient satisfaction rate varied from 89 to 97%. CONCLUSION: Local anesthesia for umbilical hernia seems safe and feasible. However, the advantages of local anesthesia are not sufficiently demonstrated, due to the heterogeneity of included studies. We, therefore, propose a randomized controlled trial comparing general versus local anesthesia for umbilical hernia repair.

Hyperbaric oxygen therapy improves colorectal anastomotic healing.

PURPOSE: Hyperbaric oxygen treatment (HBOT) has been found to improve the healing of poorly oxygenated tissues. This study aimed to investigate the influence of HBOT on the healing in ischemic colorectal anastomosis. METHODS: Forty Wistar rats were randomly divided into a treatment group that received HBOT for 10 consecutive days (7 days before and 3 days after surgery), or in a control group, which did not receive the therapy. Colectomy with an ischemic anastomosis was performed in all rats. In each group, the rats were followed for 3 or 7 days after surgery to determine the influence of HBOT on anastomotic healing. RESULTS: Five rats from each group died during follow-up. No anastomotic dehiscence was seen in the HBOT group, compared to 37.5 % and 28.6 % dehiscence in the control group on postoperative day (POD) 3 and 7, respectively. The HBOT group had a significantly higher bursting pressure (130.9 ± 17.0 mmHg) than the control group (88.4 ± 46.7 mmHg; p = 0.03) on POD 3. On POD 3 and POD 7, the adhesion severity was significantly higher in the control groups than in the HBOT groups (p < 0.005). Kidney function (creatinine level) of the HBOT group was significantly better than of the control group on POD 7 (p = 0.001). Interestingly, a significantly higher number of CD206+ cells (marker for type 2 macrophages) was observed in the HBOT group at the anastomotic area on POD 3. CONCLUSION: Hyperbaric oxygen enhanced the healing of ischemic anastomoses in rats and improved the postoperative kidney function.

The immunomodulatory nutritional intervention NR100157 reduced CD4+ T-cell decline and immune activation: a 1-year multicenter randomized controlled double-blind trial in HIV-infected persons not receiving antiretroviral therapy (The BITE Study).

BACKGROUND: The immunomodulatory nutritional product NR100157 was developed for human immunodeficiency virus (HIV)-infected individuals. We hypothesized that targeting the compromised gastrointestinal tract of HIV-infected individuals would result in systemic immunological benefits. METHODS: In a multicenter, randomized, controlled, double-blind trial, 340 HIV-1-positive adults not on antiretroviral therapy, with CD4(+) T-cell counts <800/µL, were given either NR100157 or an isocaloric and isonitrogenous control for 52 weeks. Primary outcome was CD4(+) T-cell count. Secondary outcomes included plasma viral load (pVL), safety, and tolerability. In a pilot study (n = 20), levels of CD4(+)CD25(+) and CD8(+)CD38(+) activation were measured (n = 20). The trial is registered at the Dutch Trial Register (NTR886) and ISRCTN81868024. RESULTS: At 52 weeks, CD4(+) T-cell decline showed a 40-cell/µL difference (P = .03) in the intention-to-treat population in favor of the immunomodulatory NR100157 (control vs active, -68 ± 15 vs -28 ± 16 cells/µL/year). The change in pVL from baseline was similar between groups (P = .81). In the pilot study, the percentage of CD4(+)CD25(+) was lower in the active group (P < .05) and correlated with changes in CD4(+) T-cell count (r = -0.55, P < .05). The percentage of CD8(+)CD38(+) levels was unaffected. CONCLUSIONS: The specific immunonutritional product NR100157 significantly reduces CD4(+) decline in HIV-1-infected individuals, and this is associated with decreased levels of CD4(+)CD25(+). (This nutritional intervention is likely to affect local gut integrity and gut-associated lymphoid tissue homeostasis, which in turn translates positively to systemic effects.) Clinical Trials Registration. ISRCTN81868024.

[Replacement of perioperative blood loss for cancer patients. Results of a survey among surgical departments in Germany]. / Ersatz des perioperativen Blutverlusts bei Karzinompatienten. Ergebnisse einer Umfrage in chirurgischen Kliniken in Deutschland.

BACKGROUND: The need for red blood cell units in cancer surgery is increasing. The role of the better immunological options, such as preoperative blood donation or intraoperative autologous blood salvage is not known. The aim of this survey was to clarify the transfusion setting and options for cancer patients in Germany. METHOD: A questionnaire was send to 90 directors of surgical departments in Germany. RESULTS: A total of 60 directors answered the questionnaire. In most cases the blood loss is compensated by allogenic blood transfusions. The possibility of preoperative blood donation exists in 85% of the hospitals and is offered in 3% for cancer patients. The intraoperative blood salvage is possible in 93% of the hospitals and 10% use this procedure without an additional purifying process for cancer patients. Of the hospitals 31% are able to irradiate blood collected intraoperatively, but only 11% use this for cancer patients. CONCLUSION: Perioperative blood loss is compensated by allogenic blood transfusion. The better immunological procedures, such as preoperative blood donation or intraoperative blood salvage, are not used because of the higher costs and the possible retransfusion of tumor cells.

Measurement of fetal head descent using the 'angle of progression' on transperineal ultrasound imaging is reliable regardless of fetal head station or ultrasound expertise.

OBJECTIVES: To assess whether ultrasound experience or fetal head station affects the reliability of measurement of fetal head descent using the angle of progression on intrapartum ultrasound images obtained by a single experienced operator, and to determine reliability of measurements when images were acquired by different operators with variable ultrasound experience. METHODS: One experienced obstetrician performed 44 transperineal ultrasound examinations of women at term and in prolonged second stage of labor with the fetus in the occipitoanterior position. Three midwives without ultrasound experience, three obstetricians with < 5 years' experience and three obstetricians with > 10 years' experience measured fetal head descent based on the angle of progression in the images obtained. The angle of progression was measured by two obstetricians in independent ultrasound examinations of 24 laboring women at term with the fetus in the cephalic position to allow assessment of the reliability of image acquisition. Intraclass correlation coefficients (ICCs) with 95% confidence interval (CI) were used to evaluate interobserver reliability and Bland-Altman analysis was used to assess interobserver agreement. RESULTS: In total, 444 measurements were performed and compared. Interobserver reliability with respect to offline image analysis was substantial (overall ICC, 0.72; 95% CI, 0.63-0.81). ICCs were 0.82 (95% CI, 0.70-0.89), 0.81 (95% CI, 0.71-0.88) and 0.61 (95% CI, 0.43-074) for observers with > 10 years', < 5 years' and no ultrasound experience, respectively. There were no significant differences between ICCs among observer groups according to ultrasound experience. Fetal head station did not affect reliability. Bland-Altman analysis indicated reasonable agreement between measurements obtained by two different operators with > 10 years' and < 5 years' ultrasound experience (bias, -1.09 degrees ; 95% limits of agreement, -8.76 to 6.58). The reliability of measurement of the angle of progression following separate image acquisition by two experienced operators was similar to the reliability of offline image analysis (ICC, 0.86; 95% CI, 0.70-0.93). CONCLUSIONS: Measurement of the angle of progression on transperineal ultrasound imaging is reliable regardless of fetal head station or the clinician's level of ultrasound experience.

Limited regression of central giant cell granuloma by interferon alpha after failed calcitonin therapy: a report of 2 cases.

Central giant cell granuloma (CGCG) is a benign lesion of the jaws with a sometimes locally aggressive behaviour. The most common therapy is surgical curettage which has a high recurrence rate, especially in lesions with aggressive signs and symptoms (i.e. pain, paresthesia, root-resorption and rapid growth). Alternative therapies such as interferon alpha (INFalpha) or calcitonin are described in the literature. In this study 2 patients with an aggressive CGCG are presented who were treated with INF mono-therapy. INF mono-therapy was capable of terminating the rapid growth of the lesion in both patients and induced a partial reduction. Total resolution, however, was not obtained and alternative treatment is still necessary.

Lack of detectable alterations in immune responses during sublingual immunotherapy in children with seasonal allergic rhinoconjunctivitis to grass pollen.

BACKGROUND: Recent work indicates that subcutaneous specific immunotherapy induces specific T-cell anergy, a shift in the TH1/TH2 ratio, and antibody production in favor of IgG4. There are few data on sublingual immunotherapy (SLIT), especially in children. METHODS: We assessed the proliferation of peripheral blood mononuclear cells ((3)H-thymidine incorporation) and secretion of interleukin (IL)-4, interferon (IFN)gamma and IL-5 (ELISA) after in vitro stimulation with allergen or phytohemagglutinin (PHA) in 29 children with allergic rhinoconjunctivitis receiving SLIT with grass pollen before, and after 1 and 2 years of treatment in a multicenter placebo-controlled study on the efficacy of the treatment. Further, non-specific intracellular production of IL-4, IL-13, IFNgamma, IL-2, IL-10 and IL-5 (FACS) and serum total and specific IgE and IgG4 (ELISA) were analyzed. RESULTS: Proliferation and IL-4 and IL-5 secretion after stimulation with allergen or PHA did not differ between the groups. In addition, we observed no effect of SLIT on intracellular cytokine production. IFNgamma secretion after allergen coculture was comparable between the groups. Following PHA stimulation, IFNgamma secretion was significantly higher in the SLIT group after 1 year, and a trend was observable already before and after 2 years of treatment, probably due to the inhomogeneity in the groups despite randomization (for age and asthma). No significant changes were observed for sIgE/sIgG4 ratios over time either in or between the groups. CONCLUSION: During 2 years of SLIT in children with a positive effect on rescue medication use, we observed no significant effects on in vitro T-cell immune responses or immunoglobulins. So far, pediatric studies demonstrating stable effects of SLIT on such reactions are missing, probably due to limited effects of SLIT on systemic immunologic reactions.

A prospective, randomized, double-blind, placebo-controlled multi-centre study on the efficacy and safety of sublingual immunotherapy (SLIT) in children with seasonal allergic rhinoconjunctivitis to grass pollen.

BACKGROUND: Especially in childhood, sublingual immunotherapy (SLIT) could offer advantages over subcutaneous therapy. However, limited data on its efficacy is available. METHODS: In four German centres 97 children (age 3-14 years) with allergic rhinoconjunctivitis to grass pollen were enrolled in a prospective, double-blind trial comparing SLIT (Pangramin SLIT; ALK-SCHERAX, 0.5 microg major allergens, three times per week, 32 months) with placebo. Primary endpoint was a multiple symptom-medication score for changes in seasonal diary entries between the first and third year of the study (SLIT n=39; placebo n=38). RESULTS: The multiple symptom-medication score was significantly reduced by SLIT to 77.3% of the placebo group (P=0.0498). The subsequent analysis of the single endpoints did not reveal significant differences for symptom scores in favour of SLIT (85.1% of placebo group; P=0.22). However, the medication score improved significantly (67.1% of placebo group; P=0.0025). Furthermore, secondary endpoints assessing in vivo immune responses did not differ significantly between the groups. However, retrospective analysis showed some inhomogeneity for clinical and in vitro parameters at the beginning of the study. Allergic side effects with possible relation to the study drug were reported in both groups (SLIT 49%, placebo 27%, P=0.026). CONCLUSION: Our study indicates that SLIT had a positive effect on the reduction of a multiple symptom-medication score, mainly by significantly reducing rescue medication use, but had no significant effect on symptoms alone in children with rhinoconjunctivitis to grass pollen compared with a placebo.

Long-term efficacy of dynamic graciloplasty for fecal incontinence.

PURPOSE: Patients with end-stage fecal incontinence in whom all standard medical and surgical treatment has failed or is not expected to be effective can be treated by dynamic graciloplasty. The aim of this study was to review the long-term efficacy data. METHODS: Success was defined as a greater than 50 percent decrease in the frequency of incontinent episodes. Measured physiologic parameters included enema retention time and the difference in resting and squeezing pressures with and without stimulation. Measured quality-of-life parameters included the Medical Outcomes Study Short Form 36 Health Status Questionnaire, a Fecal Incontinence TyPE Specification, the Zung Self-Rating Depression Scale, the "state" portion of the State-Trait Anxiety Inventory, and the Visual Analog Scale, which were administered at baseline and through follow-up. Independent monitors collected data as part of a multicenter trial for patients who underwent dynamic graciloplasty from May 1993 to November 1999. RESULTS: There were 129 patients entered in the study, 115 of whom met eligibility criteria and were included in the efficacy outcome analysis. Twenty-seven patients entered the study with a preexisting functioning stoma; the remaining 88 patients did not have a functioning stoma at the time of enrollment. Success was achieved in 62 percent of nonstoma patients at 12 months; these results were sustained at 18-month and 24-month follow-up assessments (55 and 56 percent, respectively). The success rate in the stoma patients increased from 37.5 percent (9 of 24 patients) at 12 months to 62 percent (13 of 21 patients) at 18 months and was 43 percent at 24 months (9 of 21 patients), which reflects the increased number of patients whose stomas were closed. Although the measured physiologic continence parameters generally improved, these changes did not correlate with continence outcome. The group of patients (stoma and nonstoma) who underwent dynamic graciloplasty showed statistically significant improvements in quality of life as measured by Medical Outcomes Study Short Form 36 physical function (P = 0.006) and social functioning (P = 0.02) assessment. CONCLUSIONS: Dynamic graciloplasty was successful in the majority of patients with end-stage fecal incontinence. This result was usually achieved by 12 months after surgery in patients who did not have stomas and by 18 months in patients who had stomas at the time of dynamic graciloplasty surgery. These various improvements conferred by dynamic graciloplasty persisted during the two-year follow-up.

Antiretroviral treatment simplification with nevirapine in protease inhibitor-experienced patients with hiv-associated lipodystrophy: 1-year prospective follow-up of a multicenter, randomized, controlled study.

BACKGROUND: Simpler and less toxic antiretroviral strategies are needed to maximize treatment compliance without sacrificing potency, at least for drug-experienced HIV-infected patients currently on regimens containing protease inhibitors (PIs). Small nonrandomized studies have suggested a beneficial role of PI-sparing regimens on lipodystrophy. OBJECTIVES: To assess the virologic, immunologic, and clinical benefit of switching the PI to nevirapine in patients with HIV-associated lipodystrophy and sustained viral suppression before entry in the study. DESIGN: Open-labeled, prospective, randomized, multicenter study. SETTING: Seven reference inpatient centers for HIV/AIDS in Spain. PATIENTS: One hundred six HIV-infected adults with clinically evident lipodystrophy who sustained HIV-RNA suppression for at least 6 months with PI-containing antiretroviral combinations. INTERVENTION: Replacement of the PI with nevirapine during 48 weeks (Group A) versus continuing the prior PI (Group B). MEASUREMENTS: Several virologic and immunologic analyses, standard and specific biochemical tests, and anthropometric and dual X-ray absorptiometry measurements. RESULTS: At week 48, an HIV-1 RNA level <400 copies/ml was maintained in 79% and 77% of patients in Groups A and B, respectively, whereas 74% and 72% of patients had viral load levels <50 copies/ml. Absolute CD4+ counts significantly increased in both groups compared with baseline values, and a significant decrease in CD38+CD8+ cells was observed in Group A (p <.01) but not in group B. Overall, no significant changes in anthropometric or body shape measurements were found after 48 weeks. Fasting total cholesterol and triglyceride levels decreased in Group A (but not in Group B) compared with baseline values (p <.05), although no significant differences were seen between groups at the end of the study. Subjects in Group A reported a better quality of life (QOL) index than controls (p <.001), with the main reason reported being the greater simplicity of the new drug regimen. CONCLUSIONS: Protease inhibitor-sparing regimens, including nevirapine, seem to be an effective alternative for PI-experienced patients. Nevirapine-based triple therapies allow maintained control of HIV-1 RNA levels and improve the immunologic response at 48 weeks of follow-up in patients with prior sustained virologic suppression. The switch to nevirapine significantly improved the lipidic profile in Group A, although there were no differences between groups at the end of the study. Additionally, no significant changes were seen in terms of lipodystrophy-related body shape changes 1 year after the PI substitution. Finally, nevirapine-containing regimens have a simpler dosing schedule, and this facilitates high adherence and improves QOL.

Safety and efficacy of dynamic graciloplasty for fecal incontinence: report of a prospective, multicenter trial. Dynamic Graciloplasty Therapy Study Group.

PURPOSE: Dynamic graciloplasty has been used for intractable fecal incontinence, and good results have been reported. The aim of this study was to assess prospectively the safety and efficacy of dynamic graciloplasty for intractable fecal incontinence in a prospective, multicenter trial. METHODS: A total of 123 adults were treated with dynamic graciloplasty at 20 institutions. Continence was assessed preoperatively and postoperatively by use of 14-day diaries. RESULTS: There was one treatment-related death. One hundred eighty-nine adverse events occurred in 91 patients (74 percent). Forty-nine patients (40 percent) required one or more operations to treat complications. One hundred seventy (90 percent) events were resolved. Sixty-three percent of patients without pre-existing stomas recorded a 50 percent or greater decrease in incontinent events 12 months after dynamic graciloplasty, and an additional 11 percent experienced lesser degrees of improvement. Twenty-six percent were not improved, worsened, or exited. In patients with pre-existing stomas, 33 percent achieved successful outcomes at 12 months. This number increased to 60 percent at 18 months. Seventy-eight percent of patients had increased enema retention time, and mean anal canal pressures improved significantly at 12 months. Significant changes in quality of life were also observed. CONCLUSIONS: Objective improvement can be demonstrated in the majority of patients with end-stage fecal incontinence treated with dynamic graciloplasty. Reduction in incontinence episodes can be correlated with improved quality of life. Adverse events are frequently encountered, but most resolve with treatment.

Continuous brachial plexus block as treatment for the Pancoast syndrome.

BACKGROUND: Six patients with severe neuropathic pain caused by a Pancoast tumor were treated with the continuous administration of local anesthetics. These patients had not responded to any other treatment, including nonsteroidal anti-inflammatory drugs, opioids, dexamethasone, tricyclic antidepressants, anticonvulsants, ketamine, and transcutaneous electric nerve stimulation. INTERVENTIONS: An axillary catheter was placed in the brachial plexus using a posterior approach that has not been described previously. A continuous infusion system of local anesthetics was delivered via a catheter. In two patients, the main purpose was to evaluate the technical possibilities and implications of this new approach. In all patients, the visual analogue scale score was evaluated until the patient died. In four additional patients, the quality of life and performance skills were recorded. RESULTS: In all patients, there was a significant reduction in the visual analog scale score, and there was an increase in performance skills and quality of life in four patients. No side effects occurred from this technique or from the continuous administration of local anesthetics. CONCLUSIONS: We conclude that neuropathic pain may be treated by local anesthetics administered through an axillary catheter placed in the brachial plexus. This technique is reversible and is preferable to destructive procedures such as cordotomy.

Human immunodeficiency virus type 1 drug susceptibility during zidovudine (AZT) monotherapy compared with AZT plus 2',3'-dideoxyinosine or AZT plus 2',3'-dideoxycytidine combination therapy. The protocol 34,225-02 Collaborative Group.

Human immunodeficiency virus type 1 (HIV-1) isolates obtained prior to and during a combination therapy trial comparing zidovudine (AZT; 3'-azidothymidine) monotherapy with AZT plus 2',3'-dideoxyinosine (ddI) or AZT plus 2',3'-dideoxycytidine (ddC) were assessed for the development of drug resistance. Drug susceptibility was measured by using two different phenotypic assays, one that requires infection of peripheral blood mononuclear cells with HIV-1 isolated from cocultures and a second based on infection of HeLa CD4+ cells with recombinant virus containing the reverse transcriptase (RT) of the clinical isolate. In addition, genotypic assessment of resistance was obtained by DNA sequencing of the RT coding region. No difference in the development of AZT resistance was noted in isolates from individuals receiving AZT monotherapy or combination therapy. However, a low frequency of ddI or ddC resistance was seen in isolates from the combination arms, which may at least partially explain the enhanced efficacy observed with these drug combinations compared with monotherapy. It was noted from DNA sequencing that a relatively high frequency of the nonnucleoside RT inhibitor resistance mutation, codon 181 changed from encoding Tyr to encoding Cys, was present in some isolates both before and during nucleoside analog combination therapy. Since these patients were unlikely to have access to nonnucleoside RT inhibitors, it is probable that this mutation preexisted at a reasonable level in the wild-type virus population. Comparisons of the AZT susceptibility assays indicated a good correlation between the phenotypic and genotypic determinations. However, direct numerical comparisons between the phenotypic assays were not reliable, suggesting that valid comparisons of different resistance data sets will require the use of the same assay procedure.

Proteolytic processing of class IV chitinase in the compatible interaction of bean roots with Fusarium solani.

Three chitinase isoenzymes, PvChiE, PvChiF, and PvChiG (molecular masses 29, 28, 27 kD, respectively), were purified from bean (Phaseolus vulgaris L. cv Saxa) roots infected with the fungal pathogen Fusarium solani f. sp. phaseoli, and their amino acid sequence was partially determined. All sequences from all three isoenzymes exactly matched deduced amino acid sequences of the bean class IV chitinase PvChi4, formerly called PR4. The N terminus of PvChif mapped to the hinge region, and the N terminus of PvChiG mapped to the catalytic domain of PvChi4. The N terminus of PvChiE was blocked. The appearance of PvChiE, PvChiF, and PvChiG correlated with an increase in protease activity in infected roots, and they could be generated in vitro by mixing extracts with high protease activity with extracts containing high amounts of PvChi4. Extracts from infected roots prepared in the presence of protease inhibitors also contained the processed forms of PvChi4, indicating that processing occurred in planta and not as an artifact of extraction. Processing of PvChi4 was not detected in incompatible interactions with a nonhost strain of F. solani and in symbiotic interactions with Glomus mosseae, and thus may be important only in compatible interactions with F. solani.

[Neuroanatomy and anaesthesiology]. / Neuro-anatomie en anesthesiologie.

The pathways of nociception, concerning dentogenic pain, are followed from the peripheral nociceptors to the cortex. The branches of the trigeminal nerve supply the semilunar ganglion. From this ganglion the trigeminal nuclei are reached, extending from the bottom of the third ventricle to the upper cervical segments. The thalamus and subsequently the cortex are receiving nociceptive information from trigeminal nuclei. Either ascendent or descendent pathways are involved concerning nociception.

The rate of percutaneous permeation of xylene, measured using the "perfused pig ear" model, is dependent on the effective protein concentration in the perfusing medium.

In order to study the dermal permeation of compounds through the skin, an in vitro model was developed which utilized pig ears perfused with autologous pig blood (de Lange, J., van Eck, P., Elliott, G. R., de Kort, W. L. A. M., and Wolthuis, O. L. (1992). J. Pharmacol. Toxicol. Methods 27, 71-77). In the present article we investigated to what extent the rate of permeation of xylene through pig ear skin is dependent on the perfusion medium used. Pig ears were exposed to xylene (10 cm2 area) for a 4-hr period (30 degrees C, relative humidity of 40-60%) and the perfusate was analyzed for xylene using gas chromatography. The rates of permeation of xylene for whole blood, blood depleted of white blood cells, and a buffer containing 4.5% albumin were similar (+/- 300 ng/min/cm2). The rate of penetration was fivefold higher when pig plasma was used and ninefold lower when albumin was excluded from the buffer. Using the buffer, we found that the rate of permeation of xylene was proportional to flow (constant protein concentration) and protein concentration (constant flow). Our data demonstrate that the measured permeation rate for xylene is, to a large degree, dependent on the effective protein concentration (mg/min) passing through the ear. Differences in this parameter could explain the variations in rates of permeation found using the different perfusion media. To avoid problems associated with the choice of receptor fluid for permeation experiments, we suggest that full blood remains the vehicle of choice, although the practical perfusion period is limited to about 6 hr. If longer perfusion periods are required, then it should be possible to reproduce results obtained with whole blood by choosing an appropriate buffer.

Hyperbaric oxygen as prophylaxis or treatment for radiation myelitis.

This animal study was designed to investigate HBO as a treatment or prophylaxis for radiation myelitis. All animals received identical spinal cord radiation doses of 69 Gy in 10 daily fractions. Group I received no HBO; group II began HBO at the onset of signs of myelitis; group III received HBO with prophylactic intent beginning 6 wk after irradiation; and group IV received both modalities on the same day, but radiation always preceded HBO by at least 4 h. HBO consisted of 90 min oxygen at 2.4 atm abs for 20 daily treatments. Animals were objectively assessed for the loss of certain neurologic reflexes indicative of four levels of myelitis. Although all animals progressed to severe myelitis, group III animals had group-averaged levels of myelitis consistently less than control. The differences were statistically significant for several weeks. Group IV animals progressed to severe myelitis much more rapidly than any other group. Additional study is justified by this trial. Key questions to be answered include the optimal timing of HBO to produce a beneficial rather than detrimental effect.