Effect of catechin and commercial preparation of green tea essence on the pharmacokinetics of l-dopa in rabbits

The aim of this study was to investigate drug interactions of L-dopa/carbidopa with catechin and green tea essence in rabbits following the simultaneous administration via an intramuscular injection of catechin or via an intragastric route for green tea essence with L-dopa/carbidopa. The results indicated that catechin at doses of 10, 20 and 50 mg/kg increased the area under the plasma concentration-time curve from time zero to the time of the last quantifiable concentration (AUC_0-t ) of L-dopa by about 69, 78 and 42%, respectively. The metabolic ratios of the AUC_0-t for 3-O-methyldopa (3-OMD)/L-dopa significantly decreased by about 56, 68 and 76% (P < 0.05), respectively. In addition, a single dose of 5/1.25 mg/kg L-dopa/carbidopa was co-administrated with 150 mg/kg green tea essence via an intragastric route with an oral-gastric tube. Comparing the related pharmacokinetic parameters of L-dopa, the clearance and metabolic ratio of L-dopa decreased by 20 and 19% (P < 0.05), respectively. In conclusion, catechin and green tea essence can significantly affect the metabolism of L-dopa by the catechol-O-methyltransferase (COMT) metabolic pathway. Catechin can enhance L-dopa bioavailability, and both catechin and green tea essence decreased 3-OMD formation. Therefore, catechin and green tea essence may increase L-dopa efficacy for Parkinson's disease treatment.

Inhibitory Effect of Anoectochilus formosanus Extract on Hyperglycemia-Related PD-L1 Expression and Cancer Proliferation

Traditional herb medicine, golden thread (Anoectochilus formosanus Hayata) has been used to treat various diseases. Hyperglycemia induces generation of reactive oxygen species (ROS) and enhancement of oxidative stress which are risk factors for cancer progression and metastasis. In this study, we evaluated hypoglycemic effect of A. formosanus extracts (AFEs) in an inducible hyperglycemia animal model and its capacity of free-radical scavenging to establish hyperglycemia-related carcinogenesis. AFE reduced blood glucose in hyperglycemic mice while there was no change in control group. The incremental area under blood glucose response curve was decreased significantly in hyperglycemic mice treated with AFE in a dose-dependent manner. AFE and metformin at the same administrated dose of 50 mg/kg showed similar effect on intraperitoneal glucose tolerance test in hyperglycemic mice. Free-radical scavenger capacity of AFE was concentration dependent and 200 μg/ml of AFE was able to reduce more than 41% of the free radical. Treatment of cancer cells with AFE inhibited constitutive PD-L1 expression and its protein accumulation. It also induced expression of pro-apoptotic genes but inhibited proliferative and metastatic genes. In addition, it induced anti-proliferation in cancer cells. The results suggested that AFE not only reduced blood glucose concentration as metformin but also showed its potential use in cancer immune chemoprevention/therapy via hypoglycemic effect, ROS scavenging and PD-L1 suppression.

Does ethnic variability exist in the systemic exposures of oatp1a2 substrates–fexofenadine in taiwanese?

The aim of this study was to investigate differences in organic anion transporting polypeptide 1A2 activity among the Taiwanese population via an analysis of 3 pharmacokinetic studies completed in a total of 103 healthy male Taiwanese subjects. The pharmacokinetics of fexofenadine was measured as an indicator of organic anion transporting polypeptide 1A2 activity. Using the Kolmogorov-Smirnov test and quantile plots, the frequency distributions of area under the concentration-time curve and concentration were shown to be tri-modal and to represent 3 pharmacokinetic phenotypes. In a comparison with published data, the mean area under the concentration-time curve of fexofenadine in the Taiwanese subjects was similar to that in American, German, and Indian subjects, but significantly different from that in some Asian populations, including Korean and Japanese ethnic groups. These results suggested that Taiwanese subjects showed genetic variation in fexofenadine pharmacokinetics that was associated with differences in organic anion transporting polypeptide 1A2 activity.

Pharmacokinetics of fexofenadine in healthy Taiwanese volunteers

The aim of presented study was to assess pharmacokinetic properties of fexofenadine in Taiwanese volunteers. Thirty-three healthy male subjects received 180mg fexofenadine. Blood samples were drawn at appropriate times. Drug concentrations of fexofenadine were measured by a LC/MS/MS method. Non-compartmental models were applied to describe the pharmacokinetic characters of fexofenadine. After oral administration of fexofenadine, the Tmax was 1.90 ± 0.81h. The Cmax was 703.76 ± 298.94ng/mL and AUC0-oo was 4582.52 ± 1812.59h´ng/mL. The elimination half-life of fexofenadine was 12.18 ± 3.61h. One of the most important determinants was to prove the similar results in the pharmacokinetics of fexofenadine in Taiwan subjects compared with the reported data of other ethnic origin.

Facile method for determination of deoxycytidine kinase activity in biological milieus

A new analytical method for determining deoxycytidine kinase (dCK) activity in biological milieus using luminescence is reported here. This method, based on utilizing adenosine triphosphate (ATP) as the sole phosphate donor in the kinase reaction and monitoring ATP consumption via a luciferase-based chemiluminescence reaction, is capable of detecting dCK activity without the use of specific substrates or radioisotope techniques. Comparing with the reverse-phase high-performance liquid chromatography method, this new method is suggested to be efficient and sensitive. Further, application of the proposed method for profiling dCK activity in cultured cancer cells revealed that a cervix cell line exhibited the highest dCK activity to gemcitabine metabolism.

In vitro and in vivo studies of pharmacokinetics and antitumor efficacy of D07001-F4, an oral gemcitabine formulation

PURPOSE

The chemotherapy agent gemcitabine is currently administered intravenously because the drug has poor oral bioavailability. In order to assess the pharmacokinetics and antitumor activity of D07001-F4, a new self-microemulsifying oral drug delivery system preparation of gemcitabine, this study was performed to compare the effect of D07001-F4 with administered gemcitabine in vitro and in vivo.

METHODS

D07001-F4 pharmacokinetics was examined by evaluation of in vitro deamination of D07001-F4 and gemcitabine hydrochloride by recombinant human cytidine deaminase (rhCDA) and in vivo evaluation of D07001-F4 pharmacokinetics in mice. Antitumor activity was evaluated by comparing the effect of D07001-F4 and gemcitabine hydrochloride in inhibiting growth in nine cancer cell lines and by examining the effect of D07001-F4 and gemcitabine in two xenograft tumor models in mice.

RESULTS

In vitro deamination of D07001-F4 by rhCDA was 3.3-fold slower than deamination of gemcitabine hydrochloride. Growth inhibition by D07001-F4 of 7 of the 8 cancer cell lines was increased compared with that seen with gemcitabine hydrochloride, and D07001-F4 inhibited the growth of pancreatic and colon cancer xenografts. In vivo pharmacokinetics showed the oral bioavailability of D07001-F4 to be 34%.

CONCLUSIONS

D07001-F4 was effective against several cancer types, was metabolized more slowly than gemcitabine hydrochloride, and exhibited enhanced oral bioavailability.

Proteome analysis of altered proteins in streptozotocin-induced diabetic rat kidney using the fluorogenic derivatization-liquid chromatography-tandem mass spectrometry method

To find new molecular markers for early diagnosis of diabetic nephropathy, we applied fluorogenic derivatization-liquid chromatography-tandem mass spectrometry to identify the differentially expressed proteins in the kidney of control and streptozotocin-induced diabetic rats. The Sprague-Dawley rats were injected with the sodium citrate buffer or streptozotocin and then killed after 1, 4, 12 and 24 weeks. The results showed that seven proteins were significantly changed after 1 week of injection. Only one protein had significantly changed after 4 weeks of injection. However, after 12 weeks of injection, the number of altered proteins rose to 10. After 24 weeks of injection, 18 proteins had altered significantly. Five common proteins were significantly altered at week 12 and 24 after injection, respectively. Importantly, these proteins appeared prior to microalbuminuria and may serve as new biomarkers that are able to improve early detection of and new drug development for diabetic-related nephropathy.

Role of pirenoxine in the effects of catalin on in vitro ultraviolet-induced lens protein turbidity and selenite-induced cataractogenesis in vivo

PURPOSE

In this study, we investigated the biochemical pharmacology of pirenoxine (PRX) and catalin under in vitro selenite/calcium- and ultraviolet (UV)-induced lens protein turbidity challenges. The systemic effects of catalin were determined using a selenite-induced cataractogenesis rat model.

METHODS

In vitro cataractogenesis assay systems (including UVB/C photo-oxidation of lens crystallins, calpain-induced proteolysis, and selenite/calcium-induced turbidity of lens crystallin solutions) were used to screen the activity of PRX and catalin eye drop solutions. Turbidity was identified as the optical density measured using spectroscopy at 405 nm. We also determined the in vivo effects of catalin on cataract severity in a selenite-induced cataract rat model. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was applied to analyze the integrity of crystallin samples.

RESULTS

PRX at 1,000 μM significantly delayed UVC-induced turbidity formation compared to controls after 4 h of UVC exposure (p<0.05), but not in groups incubated with PRX concentrations of <1,000 μM. Results were further confirmed by SDS-PAGE. The absolute γ-crystallin turbidity induced by 4 h of UVC exposure was ameliorated in the presence of catalin equivalent to 1~100 μM PRX in a concentration-dependent manner. Samples with catalin-formulated vehicle only (CataV) and those containing PRX equivalent to 100 μM had a similar protective effect after 4 h of UVC exposure compared to the controls (p<0.05). PRX at 0.03, 0.1, and 0.3 μM significantly delayed 10 mM selenite- and calcium-induced turbidity formation compared to controls on days 0~4 (p<0.05). Catalin (equivalent to 32, 80, and 100 μM PRX) had an initial protective effect against selenite-induced lens protein turbidity on day 1 (p<0.05). Subcutaneous pretreatment with catalin (5 mg/kg) also statistically decreased the mean cataract scores in selenite-induced cataract rats on post-induction day 3 compared to the controls (1.3±0.2 versus 2.4±0.4; p<0.05). However, catalin (equivalent to up to 100 μM PRX) did not inhibit calpain-induced proteolysis activated by calcium, and neither did 100 μM PRX.

CONCLUSIONS

PRX at micromolar levels ameliorated selenite- and calcium-induced lens protein turbidity but required millimolar levels to protect against UVC irradiation. The observed inhibition of UVC-induced turbidity of lens crystallins by catalin at micromolar concentrations may have been a result of the catalin-formulated vehicle. Transient protection by catalin against selenite-induced turbidity of crystallin solutions in vitro was supported by the ameliorated cataract scores in the early stage of cataractogenesis in vivo by subcutaneously administered catalin. PRX could not inhibit calpain-induced proteolysis activated by calcium or catalin itself, and may be detrimental to crystallins under UVB exposure. Further studies on formulation modifications of catalin and recommended doses of PRX to optimize clinical efficacy by cataract type are warranted.

Pharmacokinetics of p-Aminohippuric Acid and Inulin in Rabbits with Aristolochic Acid Nephropathy

The characteristics of aristolochic acid nephropathy (AAN) are interstitial fibrosis and atrophy of the proximal tubules, but with no change in glomeruli. To investigate the effects of AA on renal functions and the pharmacokinetics (PKs) of p-aminohippuric acid (PAH) and inulin, New Zealand white rabbits were used in this study. The plasma concentrations of PAH and inulin were determined by validated HPLC methods. After a single intravenous administration of 0.5 mg/kg aristolochic acid sodium (AANa), rabbits exhibited mild to moderate nephrotoxicity on the 7th day. Significant tubulointerstitial damage to kidney specimens was found, but there were no remarkable glomerular changes. Clearance rates of PAH and inulin both significantly decreased in AANa-treated rabbits. In addition, there was a significant correlation among the degree of tubulointerstitial changes and PK parameters of PAH after AANa administration, but no correlation was noted with the PKs of inulin. With mild to moderate AAN in rabbits, the renal plasma flow significantly decreased by 55%, and the glomerular filtration rate also significantly decreased by 85%. In conclusion, major renal lesions were found on proximal tubules after AANa administration. The PKs of PAH and inulin significantly changed, and kidney functions, including the RPF and GFR, were reduced.

Synthesis and structure-activity relationships of 1-benzyl-4,5,6-trimethoxyindoles as a novel class of potent antimitotic agents

A series of 1-benzyl-4,5,6-trimethoxyindoles was designed and prepared as a novel class of potent antimitotic agents acting through the colchicine binding site of tubulin. Compounds 10 and 11 showed excellent antiproliferative activity with mean IC(50) values of 26 and 27 nM, respectively, in a diverse set of human cancer lines from different organs, including a MDR+ line. They also displayed substantial antitubulin efficacy with IC(50) values of 3.5 and 2.6 muM, respectively, representing an improvement over colchicine (IC(50)=4.3 muM).

Low-loss propagation in Cr4+:YAG double-clad crystal fiber fabricated by sapphire tube assisted CDLHPG technique

Cr4+:YAG double-clad crystal fiber with an uniform 10-microm core was fabricated by using a sapphire tube as a heat capacitor to stabilize the power fluctuation of the CO2 laser in the co-drawing laser-heated pedestal growth system. The uniformity of the fiber core showed a factor of 3 improvement compared to that without the use of sapphire tube. The variation of the core diameter is within the +/-1.35-degree adiabatic criterion and has a autocorrelation length of 1.7 mm. The measured propagation loss is only 0.02 dB/cm. The sapphire tube also reduces the vertical temperature gradient during the crystal fiber growth process so the 10-microm crystal core exhibits a smooth perimeter. The sapphire tube assisted system can be applied to the growth of many other optical crystal materials.

Pharmacokinetics and nephrotoxicity of aristolochic acid in rabbits

Aristolochic acids (AAs) which exist in plants of the genus Aristolochia are the toxins responsible for aristolochic acid nephropathy (AAN). To investigate the pharmacokinetics and nephrotoxicity of AAs, rabbits were used in this study. The plasma concentrations of the main components of AAs, aristolochic acid I (AA I) and aristolochic acid II (AA II), were determined by a validated high-performance liquid chromatographic method. After intravenous administration of different doses (0.25, 0.5, 1.0, and 2.0mg/kg) of aristolochic acid sodium (AANa) to 4 respective groups of rabbits (n=6 for each dose), linear relationships between the doses of AA I and AA II and the area under the plasma concentration curve (AUC) were found to exist (p<0.001). AANa was also given in escalating doses (0.5, 1.0, and 2.0mg/kg) to the same rabbits at 7-day intervals. The clearance rates of both AA I and AA II significantly decreased with the escalating dose (p<0.001). A nonlinear relationship between the dose and AUC was obtained. Kidney specimens of rabbits were obtained to observe morphological changes on days 1 and 7 after AANa administration. The renal lesions caused by AAs consisted of progressive and dose-dependent tubular damage. However, no remarkable changes in the morphology of glomeruli were observed.

Pharmacokinetics of nifedipine in Taiwanese

To elucidate the pharmacokinetics of nifedipine in Taiwanese, a retrospective review of nifedipine bioequivalence studies completed in Taiwan in the past 5 years was conducted. A total of 198 healthy male volunteers were given a single dose of a 10 mg Adalat capsule as a reference drug after overnight fasting. Pharmacokinetic parameters derived from Adalat administration were calculated by non-compartmental analysis with the WinNonlin program. After oral administration of an immediate-release dosage form of a 10 mg nifedipine capsule to Taiwan residents, a skewed distribution with no clear evidence of bimodality of pharmacokinetic parameters was observed. The mean Cmax was 143.12+/-53.48 ng/ml, the mean AUC was 293.77+/-115.62 ng.h/ml, the mean T1/2 was 3.08+/-1.61 h, and the median value of Tmax was 0.61 h. Compared with other published studies, the Cmax and AUC of nifedipine after 10 mg administration were significantly higher in Taiwanese than in British and American subjects. However, the Cmax and AUC were similar to those of Indian and Mexican subjects. According to the antimode of AUC distribution of 22.5 ng.h/ml/mg proposed by Kleinbloesem, 69.7% of Taiwanese can be categorized as slow metabolizers. Based on the results in this study, the majority of Taiwanese show lower activity of nifedipine metabolism.

A prospective randomized multi-center study for the treatment of lumbar spinal stenosis with the X STOP interspinous implant: 1-year results

Patients suffering from neurogenic intermittent claudication secondary to lumbar spinal stenosis have historically been limited to a choice between a decompressive laminectomy with or without fusion or a regimen of non-operative therapies. The X STOP Interspinous Process Distraction System (St. Francis Medical Technologies, Concord, Calif.), a new interspinous implant for patients whose symptoms are exacerbated in extension and relieved in flexion, has been available in Europe since June 2002. This study reports the results from a prospective, randomized trial of the X STOP conducted at nine centers in the U.S. Two hundred patients were enrolled in the study and 191 were treated; 100 received the X STOP and 91 received non-operative therapy (NON OP) as a control. The Zurich Claudication Questionnaire (ZCQ) was the primary outcomes measurement. Validated for lumbar spinal stenosis patients, the ZCQ measures physical function, symptom severity, and patient satisfaction. Patients completed the ZCQ upon enrollment and at follow-up periods of 6 weeks, 6 months, and 1 year. Using the ZCQ criteria, at 6 weeks the success rate was 52% for X STOP patients and 10% for NON OP patients. At 6 months, the success rates were 52 and 9%, respectively, and at 1 year, 59 and 12%. The results of this prospective study indicate that the X STOP offers a significant improvement over non-operative therapies at 1 year with a success rate comparable to published reports for decompressive laminectomy, but with considerably lower morbidity.

Determination of mephenoxalone in human plasma sample by high-performance liquid chromatography-fluorescence detection

A simple and sensitive high-performance liquid chromatographic method involving fluorescence detection was developed for the determination of mephenoxalone in human plasma. A Cosmosil 5C18-MS column (250 mm x 4.6 mm I.D., 5 microm) was used as stationary phase and the mobile phase consisted of water-acetic acid-acetonitrile (200:1:300) at a flow-rate of 1.0 ml/min. The fluorescence absorbance was monitored at 280 nm for excitation wavelength and 310 nm for emission wavelength. Temperature control was kept at 40 degrees C for the column. The limit of quantitation achieved was 10 ng/ml, and the standard curve was found to be linear in the concentration range of 10-10,000 ng/ml. Under these analytical conditions, a sufficient mephenoxalone plasma concentration profile could be obtained for pharmacokinetic study.

Treatment of giant cell tumor of the distal radius

The results of surgical treatment of giant cell tumors of the distal radius were reviewed in 12 patients between 1982 and 1995. All 12 patients had Grade III lesions. Six of the 12 patients were treated using intralesional curettage with local excision, and the other six patients underwent en bloc resection with total condyle (four of the six by osteoarticular allograft, and the other two by fibular autograft) reconstruction with the aim of preserving the functional joint. There were no early or late complications such as infection, graft fracture, implant failure, or nonunion. No local tumor recurrence was seen in either group during the average followup of 6 years (range, 3-16 years). The best functional result was seen in the patients treated with intralesional curettage. The functional result of the resection group was good, achieving an average of 69% (range, 56%-83%) of their range of motion and 70% (range, 63%-77%) of their grip strength on the contralateral side. Intralesional excision should not be excluded as a possible treatment of Grade III lesions, although en bloc resection was used more commonly for these lesions because of tumor surgery reasons. Grade III lesions were treated with curettage when the tumor did not invade the wrist, destroy more than 50% of the cortex, or break through the cortex with an extraosseous mass in more than one plane. Reconstruction with osteoarticular allograft after en bloc resection is recommended in this non-weightbearing joint when there is contraindication for curettage of the lesion.

Butachlor, a suspected carcinogen, alters growth and transformation characteristics of mouse liver cells

Butachlor is a widely used herbicide in Asia and South America. Previous investigations have indicated that it is a suspected carcinogen. To understand more about the biological effects of butachlor on cultured cells and the mechanism(s) of its carcinogenicity, we studied the alteration of the growth characteristics that was induced by butachlor in normal mouse liver cells (BNL CL2). This study demonstrates that butachlor decreases the population-doubling time of BNL CL2 cells, suggesting that it stimulates cell proliferation. To support this finding, a thymidine incorporation assay was conducted and a similar result that butachlor stimulates cell proliferation was elucidated. In addition, we show that butachlor increases the saturation density of the BNL CL2 cells. When combined with the tumor initiator N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), butachlor transforms cells efficiently, as demonstrated by loss of contact inhibition. These findings indicate that butachlor alters the growth characteristics of BNL CL2 cells and suggest that butachlor may induce malignant transformation through stimulation of cell proliferation, alteration of cell cycle regulation, and suppression of cell density-dependent inhibition of proliferation.

Experimental observation of the slowdown of optical beams by a volume-index grating in a photorefractive LiNbO3 crystal

We investigate the group velocity of light in a one-dimensional volume-index grating inside a photorefractive LiNbO(3) crystal. The slowdown of the group electromagnetic propagation is observed experimentally by tuning of the wave number of the optical beam close to the outside edge of the forbidden bandgap. We obtain a large group index of up to 7.5 in a 3.5-cm crystal sample. The group index is compared with the result of a theoretical derivation. The results are presented and discussed.

Follow-up evaluation of resected lumbar vertebral chordoma over 11 years: a case report

STUDY DESIGN

A case report with an 11-year follow-up assessment after resection and reconstruction for lumbar chordoma is given. The literature relevant to this topic is reviewed.

OBJECTIVES

To report the long-term outcome in a case of lumbar chordoma, to review the literature on vertebral chordoma, and to outline the rationale for surgical resection in such cases.

SUMMARY OF BACKGROUND DATA

Chordoma is a malignant bone tumor that grows slowly, often recurs locally, and metastasizes late. Although different treatment approaches exist, including radiation and surgery, the only curative treatment is early and complete surgical excision of the tumor. Immediate spinal stability must be achieved with appropriate replacement or bone graft with rigid fixation.

METHODS

The 11-year follow-up evaluation of a 42-year-old woman with L3 and L4 vertebral body chordoma treated with complete removal, femoral shaft allograft replacement, fusion, and rigid metal fixation is reported. The patient was observed with serial physical examinations, radiographs, and laboratory studies over 11 years.

RESULTS

At this writing, 11 years after the resection of the L3 and L4 chordoma, the patient is asymptomatic without evidence of recurrence or metastasis.

CONCLUSIONS

As reported, vertebral chordomas are not curable, but the authors' experience contradicts this. The surgeon should aim at a wide, or at least a marginal, excision followed by a stable reconstruction.

Phenanthrenequinone-doped poly(methyl methacrylate) photopolymer bulk for volume holographic data storage

We present the design and fabrication of a phenanthrenequinone-doped poly(methyl methacrylate) photopolymer material. Large blocks of samples were made, and the material showed negligible shrinkage after optical exposures. We recorded and reconstructed 250 holograms at a single spot, using a 1-cm(3) block.

Optimal conditions for thermal fixing of volume holograms in Fe:LiNbO3 crystals

We analyze and compare two typical recording and thermal fixing procedures of a volume hologram in a Fe:LiNbO(3) crystal (low-high-low procedure and high-low procedure). We consider the kinetics of the recording, compensating, and developing processes by taking into account the ratio of the conductivities between the protons and the electrons as a function of temperature. From the analysis the optimal environmental conditions (in terms of the fixing temperature and the compensation time) for each fixing procedure can be deduced for a crystal with given material parameters.

Metabolic kinetics of p-aminobenzoic acid in rabbits

The metabolic kinetics of p-aminobenzoic acid (PABA) in rabbits was studied. PABA is predominantly metabolized by acetylation and glycine conjugation to form p-acetamidobenzoic acid (PAABA), p-aminohippuric acid (PAHA), and p-acetamidohippuric acid (PAAHA). After PABA IV administration (20 mg/kg) to rapid (n=16) and slow (n=8) acetylation rabbits, PABA was eliminated rapidly. The half-lives of PABA were 7.01+/-0.32 min in rapid acetylation rabbits and 7.08+/-0.78 min in slow acetylation rabbits. Significant differences were obtained in formation of PAABA and PAHA formed from PABA in both acetylation phenotype rabbits. The formation fraction of PAABA, formed by acetylation of PABA, was 0.8029+/-0.0267 in rapid acetylators and 0.2385+/-0.0428 in slow acetylators (p<0.001). PAHA formed from PABA was 0.0462+/-0.0102 in rapid acetylators and 0. 6652+/-0.0562 in slow acetylators (p<0.001). Only 0.0156+/-0.0030 of PABA could be detected as PAAHA in rapid acetylation rabbits which was obtained by acetylation of PAHA. After individual IV injection of PAHA, PAAHA, and PAABA to both phenotypes of rabbits, PAABA and PAAHA were eliminated in their unchanged forms whereas PAHA was further acetylated to form PAAHA. The formation fraction of PAAHA formed from the acetylation of PAHA was 0.4408+/-0.0570 in rapid acetylators and 0.0539+/-0.0084 in slow acetylators (p=0.002). From the results obtained, metabolic pathways of PABA show significant differences in both acetylation phenotypes of rabbits. Acetylation is the major metabolic route of PABA in rapid acetylation rabbits, while glycine conjugation is more predominant in slow acetylation rabbits.

Management of aggressive benign and malignant bone tumors of the shoulder region

BACKGROUND

The shoulder girdle is one of the most common sites of aggressive malignant and benign bone tumors. Curative resections and sparing of the limb are possible. However, reconstruction methods remain a challenge and the functional results vary.

METHODS

Fourteen patients with aggressive benign or malignant bone tumors about the shoulder girdle who were treated with surgical resection with possible need for reconstructions were retrospectively analyzed. There were 8 men and 6 women. Their ages ranged from 15 to 70 years; the mean age at operation was 36 years. Ten patients had malignant bone tumors and four had extensive giant-cell tumors. A variety of reconstructive procedures were performed after resection of the tumors. The choice of procedure depended on the type of resection and the needs of the patients. Supplementary chemotherapy or radiotherapy was undertaken after surgical procedures in 9 patients.

RESULTS

The length of follow up ranged from 16 months to 10 years. The functional results were described and graded quantitatively according to the functional rating system of the Musculoskeletal Tumor Society. Overall, 6 patients achieved excellent and good shoulder functions at follow-up examination, while 8 acquired fair or poor functional results. Four patients died from lung metastasis, while 10 survived and are disease free. Resection of the glenoid cavity and the proximal part of the humerus with loss of the abductor mechanism resulted in poor function of the shoulder.

CONCLUSION

The choice of treatment options depended upon the staging of tumors, the extent of resection, the needs of individual patients, the preservation and reconstruction of rotator cuff, the experience of surgeons, and the facilities at the hospital. The functional results were related to the area of involvement and the type of resection. The preservation of the abductor mechanism provided good functional results.

Video-assisted thoracoscopic surgery to the upper thoracic spine

BACKGROUND

The standard open technique for exposure of the upper thoracic spine, T1-T4, usually requires a difficult thoracotomy. From November 1, 1995 to June 30, 1997, eight patients underwent video-assisted thoracoscopic spinal surgery in our institute to treat their upper thoracic spinal lesions endoscopically.

METHODS

A new approach, the so-called "extended manipulating channel method," was used in this series that allows the combined use of video-assisted thoracoscopy and conventional spinal instruments to enter the chest cavity freely for the procedures. Patients' ages ranged from 44 to 89 years (average, 60 years). Definitive diagnoses included two pyogenic spondylitis and six spinal metastases. Five patients presented initially with myelopathy.

RESULTS

There were no deaths or neurologic injuries associated with this technique. The mean surgical time was 3.1 h. The mean duration of chest tube retention was 3.3 days. The mean total blood loss was 1,038 ml, and two patients had a blood loss of more than 2,000 ml owing to bleeding from epidural veins or raw osseous surfaces. Complications included one superficial wound infection and one subcutaneous emphysema that resolved spontaneously. In this series, there was no need of conversion to open thoracotomy for the patients.

CONCLUSIONS

The thoracoscopy-assisted spinal technique using the extended manipulating channels, usually 2.5-3.5 cm, allows variable instrument angulations for manipulation. The mean surgical time (3.1 h) was considered no longer than for an open technique for the equivalent anterior procedure. Such an approach can achieve less procedure-related trauma and has proved to be a good alternative to other treatment modalities.

Treatment of fibrous dysplasia involving the proximal femur

Twenty-two patients with fibrous dysplasia in the femoral neck or trochanteric area were treated with curettage and bone grafting with a sliding hip compression screw and plate. Follow-up ranged from 2 to 6 years (average: 4 years). Fourteen patients had monostotic and 8 had polyostotic disease. Four patients had pathologic fractures. Bone grafting included a deep-frozen allogeneic cortical strut and cancellous bone. After implanting the lag screw and cortical strut, the remaining defect space was filled with iliac bone. Postoperatively, all patients had good bone healing and complete incorporation of the implanted graft. There were no recurrences or complications, and functional results were rated as good and excellent.

Subtalar distractional realignment arthrodesis with wedge bone grafting and lateral decompression for calcaneal malunion

BACKGROUND

The purpose of this study was to evaluate prospectively the efficacy of subtalar distractional realignment arthrodesis in the treatment of calcaneal malunion associated with subtalar arthritis, collapse of height, talonavicular subluxation, malalignment of the heel axis, and widening heel with calcaneofibular abutment.

METHODS

Thirty-four patients with severe calcaneal malunion were treated with a lateral approach, lateral decompression, medial subtalar capsulotomy, and distraction and realignment of the subtalar joint with an anteriorly and laterally tapered wedge bone graft. The patients were evaluated with a functional rating scale and radiographs, both before and after surgery.

RESULTS

Thirty-two of the 34 patients were evaluated at a mean of 71 months (range, 60-92 months) after the arthrodesis. Solid subtalar fusion was achieved in 31 of the 32 patients. The average gain of subtalar distraction was 12 mm. Neutral or mild valgus alignment was achieved in 26 of the 32 patients. The mean postoperative score (83) showed significant improvement over the mean preoperative score (47). Overall, the functional rating scale revealed excellent or good results in 26 patients and fair results in 6 patients.

CONCLUSION

Coupled with wedge bone grafting, the subtalar distractional realignment arthrodesis achieved restoration of hindfoot height and axial alignment with a good union rate and significant improvement in the majority of patients with calcaneal malunion.

Semistructural allografting in bone defects after curettage

BACKGROUND AND OBJECTIVES

A variety of aggressive benign bone tumors often require wide bone and soft tissue excision for adequate local control, but this creates a large defect and a seriously weakened extremity. Restoration of limb function presents a difficult problem.

METHODS

The treatment of 104 patients with space occupying lesions of the long bone were analyzed. Deep-frozen (-70 degrees C) cortical strut allografts with or without allogeneic cancellous bone graft were implanted into the defects after extensive intralesional curettage. Thirty-six patients had fibrous dysplasias, 29 unicameral bone cysts, 22 giant cell tumors, 12 aneurysmal bone cysts, 3 benign fibrous histiocytomas, and 2 ossifying fibromas. Fifty-six patients had pathologic fracture. The average volume after curettage was 210 ml (range 60-460 ml). The average follow-up period was 50 months.

RESULTS

At follow-up evaluation, the radiographs demonstrated complete incorporation of the allogeneic implant and new bone formation in the cavity in 83% of the patients (86/104). All fractures healed. There was no local recurrence or fracture of the cortical graft; neither were there other serious complications except one avascular necrosis of the femoral head. Good or excellent functional results were found in 97% (101/104) of the patients.

CONCLUSIONS

For large osseous defects, the reconstructive technique using cortical stent allograft provides increased strength, easy fixation, remodeling of the cystic defect, and healing of the fracture and prevents deformity. However, remodeling occurs slowly and may never be complete.

Long-term continuous infusion of propofol as a means of sedation for patients in intensive care unit: relationship between dosage and serum concentration

BACKGROUND

We studied the effect of long-term continuous propofol infusion in patients who were utilizing mechanical ventilation in intensive care unit. The purpose of our study was to identify the appropriate dosage of propofol and to monitor the relating serum level that would provide satisfactory sedative and hypnotic effects to the patients, i.e., to procure a Ramsay Sedation Scale (RSS) value between 2 and 3.

METHODS

Ten mechanically ventilated ICU patients were studied. The syringe pump was set to deliver propofol at a rate of 1 mg/kg/h without an initial loading dose. After continuous infusion of propofol for 24 h, in each patient 5 ml of whole blood was sampled daily for one week. All samples were analyzed for serum level of propofol by high performance liquid chromatography.

RESULTS

When the Ramsay Sedation Scale (RSS) value was between 2 and 3, the mean dosage of infused propofol was 0.71 +/- 0.31 mg/kg/h (ranging from 0.58 to 1.27 mg/kg/h) and the mean plasma concentration was 0.58 +/- 0.22 microgram/ml (ranging from 0.20 to 0.86 microgram/ml). The lipid serum level was measured in three patients whose infusion duration was greater than 14 days. The respective level was 321 mg/dl, 139 mg/dl, and 99 mg/dl. The first patient died from multiple organ failure as a result of multiple trauma. Four patients simultaneously received infusion of propofol and muscle relaxant.

CONCLUSIONS

We concluded that propofol infusion given at a rate of 0.71 +/- 0.31 mg/kg/h and a plasma concentration level of less than 1 microgram/ml would be sufficient to produce a sedation with RSS value between 2 and 3.

Analysis of techniques for video-assisted thoracoscopic internal fixation of the spine

Between November 1, 1995, and January 31, 1996, four separate thoracoscopic spinal fixation surgeries were performed via extended manipulating channels using the so-called three-portal technique. The diagnoses included three spinal metastases and one T11 burst fracture. All patients had myelopathy at presentation. Using the three-portal technique, the conventional spinal instruments and fixation devices could be passed freely through the extended manipulating channels (usually 3-4 cm) into the chest cavity and manipulated by techniques similar to those used in standard open procedures. A reduction-fixation spinal plate with variable screw and plate anchoring angles was successfully inserted in the procedures. The total length of the operation ranged from 3.5 to 5 h (average 4.3 h), and the total blood loss was 1000-2500 ml (average 1500 ml). There were no intraoperative deaths, and no patient showed neurological deterioration following the procedures. On the basis of these results, we believe that the combination of video-assisted thoracoscopy and conventional spinal instruments presented in this report would be an ideal method for performing these procedures. Throughout the operation, only one trocar was employed for introducing the thoracoscope. The thoracoports were used temporarily during tumor tissue retrievals. This technique makes thoracoscopy-assisted spinal fixation simple and easy. It allows greater control of intraoperative vessel bleeding and reduces the number of portals required during the procedure (on average to 3). In addition, the technique reduced the amount of endoscopic materials required for the procedure, thus reducing the cost of treatment.

Preparation and characterization of heparin-containing SBS-g-DMAEMA copolymer membrane

The grafting of dimethyl amino ethyl methacrylate (DMAEMA) onto styrene-butadiene-styrene triblock copolymer (SBS) membrane was subsequently conducted by UV-radiation induced graft copolymerization without degassing to obtain the SBS-g-DMAEMA copolymer membrane. The substituted amino groups on the SBS-g-DMAEMA graft copolymer membrane were quaternized with iodomethane, and then the membrane was treated with heparin to prepare the heparin-containing SBS-g-DMAEMA copolymer membrane (SBS-g-DMAEMA-HEP). The graft copolymer membrane (SBS-g-DMAEMA) and the heparin-containing SBS-g-DMAEMA copolymer membrane (SBS-g-DMAEMA-HEP) were characterized by FTIR spectroscopy. The heparin content was determined by toluidine blue heparin assay. Contact angle, water content, and protein adsorption of fibrinogen and albumin experiments were also performed to evaluate the effect of graft amount and heparin content on the biocompatibility of SBS-g-DMAEMA and SBS-g-DMAEMA-HEP graft copolymer membranes. By using Kaelble's equation, the surface tension of SBS-g-DMAEMA and SBS-g-DMAEMA-HEP were determined. It was found that with increasing grafting amount and the heparin content, the surface tension and water content of SBS-g-DMAEMA membrane increased, whereas the contact angle decreased. The amount of the adsorption of albumin and fibrinogen decreased with increasing graft amount and heparin content. However, there was a minimum for adsorption of proteins in the SBS-g-DMAEMA and SBS-g-DMAEMA-HEP membranes.

Video-assisted thoracoscopic treatment of spinal lesions in the thoracolumbar junction

BACKGROUND

The endoscopic treatment of spinal lesions in the thoracolumbar junction (T11-L2) poses a great challenge to the surgeon. From November 1, 1995 to December 31, 1996, we successfully used a combination of video-assisted thoracoscopy and conventional spinal instruments to treat 38 patients with anterior spinal lesions. Twelve of them had lesions in the thoracolumbar junction.

METHODS

The so-called extended manipulating channel method was used to perform vertebral biopsy, discectomy, decompressive corpectomy, interbody fusions, and/or internal fixations in these patients. The size of the thoracoscopic portals was greater than usual in order to allow conventional spinal instruments and a thoracoscope to enter the chest cavity freely and be manipulated by techniques similar to those used in standard open surgical procedures. In this series, the procedures were performed by using either a three-portal approach (2. 5-3.5 cm) or a modified two-portal technique involving a 5-6 cm larger incision and a small one for introducing the scope.

RESULTS

None of the operations resulted in injury to the great vessels, internal organs, or spinal cord. The total time for the operation ranged from 1.5 to 4.5 h (average, 3); and the total blood loss ranged from 50 to 3000 cc (average, 1050). One patient was converted to an open procedure due to severe pleural adhesion. Complications included two instances of transient intercostal neuralgia, one superfical wound infection, and one residual pneumothorax.

CONCLUSIONS

The video-assisted technique with the extended manipulating channel method presented in this report simplifies thoracoscopic spinal surgery in the thoracolumbar junction and makes it easier. It avoids division of the diaphragm, removal of the rib, and wide spread of the intercostal space, and it allows greater control of intraoperative vessel bleeding. Using this technique, the number of portals required during the procedure can be reduced. In addition, the technique reduces the endoscopic materials required, thus lowering overall cost. It is an effective and promising approach.

Low-flow anesthesia in adult orthotopic liver transplantation: a preliminary clinical experience

BACKGROUND

Anesthesia in orthotopic liver transplantation (OLT) may carry with complex hemodynamic, body temperature, and metabolic alterations. Although OLT cases increased in recent years in Taiwan, experiences remained limited. Notable advantage of low flow anesthesia may include reduced consumption of anesthetic gases and vapors, reduced environmental pollution and cost-saving. This study investigated patient profiles and the feasibility of low-flow rebreathing technique for adult orthotopic liver transplantation.

METHODS

Since June 1996, there were six OLT patients who received low flow anesthesia with isoflurane. All patients received hepatic veno-venal anastmosis (so-called piggy back procedure). Two patients were excluded from this study because of different surgical procedure (total occlusion of inferior vena cava and inferior vena cava veno-venal anastmosis). During maintenance of anesthesia, isoflurane was carried by a mixture of oxygen and air at a total fresh gas flow of 0.6 L/min. Alongside with the standard anesthesia machine and physiologic monitors, a newly designed Swan-Ganz catheter was introduced to measure and record cardiac output, systemic vascular resistance, pulmonary artery pressure, central venous pressure, and core temperature in a real-time manner. Blood samples were collected at 6 predetermined time-points in each patient for analysis of arterial blood gases, electrolytes, lactate and glucose concentrations.

RESULTS

The anesthetic time was 916 +/- 26 min (900 to 930 min). All patients regained their consciousness within 30 min after completion of surgery. The hemodynamics were relatively stable except after reperfusion of the liver. There was a significant decrease in mean arterial blood pressure, which occurred with accompaniment of a reduction of systemic vascular resistance and increased cardiac output. Arterial blood gas, electrolyte, and glucose were, however, maintained within acceptable limits. Blood lactate was progressively increased and reached its peak after reperfusion of the liver until the end of surgery. The core temperature was well maintained above 34 degrees C. No patient developed hypoxia or hypercapnia.

CONCLUSIONS

Low-flow rebreathing anesthetic technique maintained acceptable patient profiles and good body temperature preservation in orthotopic liver transplantation. These characteristics make it a promising method in maintenance of anesthesia for OLT.

Propofol anesthesia in a patient with Isaacs syndrome--report of a case and literature review

Isaacs syndrome is an unusual lower motor neuron disease characterized by myokymia (muscle twitching), muscular stiffness, and decreased tendon reflexes. We reported a patient who was affected with this rare disease, with manifestation of involuntary muscular contractions and required general anesthesia for bilateral tonsillectomies. Understanding the presentation and characterization of this unusual disease may be helpful in making choice of anesthetics or anesthetic techniques. Its possible mechanisms of action and its specific considerations in anesthesia in the literature are reviewed and discussed.

Allogeneic cortical strut for benign lesions of the humerus in adolescents

Allogeneic cortical strut associated with or without cancellous bone grafting for benign adolescent humeral shaft lesions is an alternative management option offering a good chance of stabilization and healing. This study monitored 16 patients who had been treated with this surgical method from 1988 to 1993. There were nine boys and seven girls between the ages of 11 and 16 years (average, 14). Eleven patients had unicameral bone cysts; two had aneurysmal bone cysts; and three had fibrous dysplasia. All 16 patients received fresh-frozen (-70 degrees C) cortical strut inlay grafts in the humeral shaft defect after subtotal excision of the large lesions. No intramedullary rod or plate was used. The follow-up period ranged from 26 to 58 months (average, 41). There were no local recurrences or fractures of the shaft or allograft implants. The radiographs of all humeri revealed the cortical grafts to be well incorporated with new bone formation in the cavity. The overall functional results were good and excellent. This reconstruction with biologically safe and active material provided increased strength and prevented refracture.

A dose-dependent pharmacokinetic study on caffeic acid in rabbits after intravenous administration

The dose-dependent pharmacokinetics of caffeic acid (CA) were studied in rabbits. Three different doses (5, 10, and 25 mg kg-1) were administered intravenously to six rabbits each. The concentration-time profiles for CA could be fitted by a two-compartment model for each dose. The results showed that total-body clearance and elimination rate constant from the central compartment (k10) after a 5 mg kg-1 dose were greater than those after the other two doses. Furthermore, the terminal elimination half-life (beta half-life) and mean residence time (MRT) after a 5 mg kg-1 dose were less than after the other doses. The AUC value increased linearly with dose within the range of 10-25 mg kg-1. Most of the unchanged caffeic acid was excreted in the urine within 2 h. The percentage of unchanged caffeic acid excreted in the urine was 63.4, 60.0, and 55.4% after doses of 5, 10, and 25 mg kg-1, respectively, which was not significantly different. However, significant differences in the renal clearances and renal excretion rate constants were observed with a 5 mg kg-1 dose compared to the other doses. On the other hand, nonrenal clearances and nonrenal excretion rate constants showed no dose-related differences. The differences observed in total-body clearance, k10, beta half-life, and MRT between a 5 mg kg-1 dose and the other doses can be explained on the basis of the differences in renal clearance and renal excretion rate constants.

Total knee arthroplasty in a rheumatoid arthritic knee with large geode: a case report

Geodes (subchondral cysts) are a well-known manifestation of rheumatoid arthritis. Solitary cysts or cysts larger than 2 cm are not generally found in the knee joint of patients with rheumatoid arthritis (RA). We report a case of RA involving both knees with a giant geode over the right proximal tibia. Surgical treatment was performed including synovectomy, cyst enucleation and packing of autogenous bone chips followed by primary total knee arthroplasty. The postsurgical result was excellent with the knee restored to good function and complete healing of the cystic lesion.

Preparation and properties of SBS-g-DMAEMA copolymer membrane by ultraviolet radiation

A styrene-butadiene-styrene triblock copolymer (SBS) membrane was prepared by solvent casting. Grafting of dimethyl amino ethyl methacrylate (DMAEMA) to this SBS membrane was subsequently conducted by ultraviolet radiation-induced graft copolymerization without degassing to obtain a SBS-g-DMAEMA copolymer membrane. The graft copolymer was characterized by infrared spectroscopy and scanning electron microscopy. The degree of grafting and the mechanical properties of SBS and SBS-g-DMAEMA were measured. Contact angle, water content, and protein absorption of fibrinogen and albumin experiments were also performed to evaluate the biocompatibility of SBS-g-DMAEMA graft copolymer membranes. It was found that the degree of grafting was related to the irradiation time, DMAEMA concentration, and temperature. The tensile strength of the SBS-g-DMAEMA membrane increased with an increase in the degree of grafting. By using Kaelble's equation and the contact angle data, the surface tension of SBS-g-DMAEMA was determined. It was found that with an increase in the degree of grafting, the surface tension and water content of SBS-g-DMAEMA membrane increased, whereas the contact angle decreased. The amount of absorption of albumin and fibrinogen decreased with an increase in amount of grafting. However, there was a minimum for the adsorption of proteins in the SBS-g-DMAEMA membrane.

Distal chevron osteotomy with intra-articular lateral soft-tissue release for treatment of moderate to severe hallux valgus deformity

We retrospectively reviewed the results of 32 patients (38 feet), with hallux valgus angles between 35 degrees and 60 degrees, who were treated by standard distal chevron osteotomy and intra-articular lateral soft tissue release. The average follow-up period was 5.2 years (4-7 years). The preoperative intermetatarsal angle averaged 14.4 degrees, and the postoperative angle averaged 7.7 degrees. The preoperative hallux valgus angle averaged 42.7 degrees, and the postoperative angle averaged 18.8 degrees. Subjectively, the satisfaction rate in terms of symptom improvement, cosmetic appearance and function was over 90%. Avascular necrosis of the first metatarsal head was not found in our series, which indicated that additional lateral soft tissue release is not contraindicated in combination with chevron osteotomy. Based on the level of satisfaction in our series, we conclude that the combination of distal chevron osteotomy and intraarticular lateral soft tissue release has broader application than the chevron osteotomy alone for patients with hallux valgus deformity.

Ankle arthrodesis with cross screw fixation. Good results in 36/40 cases followed 3-7 years

Tibiotalar arthrodesis by an anterior approach, using internal compression with cancellous crews, offers wide exposure, good possibilities of correcting deformities, and good bony apposition. From 1987 to 1991, we used this technique in 42 ankle joints (40 patients). The indications were posttraumatic arthrosis, sequelae of septic arthritis, necrosis of the talus and failed ankle arthrodesis. In 13 ankles with severe deformity, a bone graft was also used. 38 patients (40 ankle joints) were available for follow-up after 4 (3-7) years. Solid union was achieved in 38 ankles after an average of 13 weeks. The clinical result was good-to-excellent in 36 ankles. We conclude tha this is a simple and effective method for ankle arthrodesis in both low-risk and, coupled with bone grafting, in properly selected high-risk patients.

Contradirectional two-wave mixing with partially coherent waves in photorefractive crystals

We investigate contradirectional two-wave mixing with partially coherent waves in photorefractive crystals in the nondepleted pump regime. Equations governing the propagation of the self-coherence function and the mutual-coherence function of the signal wave and the pump wave are derived and simulated numerically. Numerical solutions of these equations are in excellent agreement with the experimental measurements.

Anatomic position of a herniated nucleus pulposus predicts the outcome of lumbar discectomy

The purpose of this study was to determine whether the anatomic position of a lumbar disc herniation has any significant effect on the clinical outcome of lumbar discectomy. Between January 1988 and March 1993, 80 patients with simple disc herniations underwent lumbar discectomy for herniated nucleus pulposus. We reviewed preoperative computed tomography scans after discography and magnetic resonance imaging of the lumbar spine. Disc herniations were classified as central, paracentral, intraforaminal, extraforaminal, or multiregional broad-based protrusions. The Smiley-Webster evaluation scale, which divided patients into groups with excellent, good, fair, and poor clinical outcome and evaluated the long-term need for pain medication, was applied. The post-operative evaluation period ranged from 6 to 48 months. The clinical outcome was then correlated with the different positions of herniations. The frequencies of the clinical outcomes were compared using the chi 2 test. We found a poorer clinical outcome that was statistically significant in patients with central herniations and with multiregional protrusions. Most herniations occurred at the L4-L5 level (58.7%). However, the level of disc herniation was not found to be a predictor of clinical outcome. Form and anatomic position of the lumbar disc herniation are of prognostic value for the outcome of lumbar discectomy. Further studies are required to confirm our preliminary results and eventually help improve surgical indications for lumbar discectomy.

Determination of p-aminobenzoic acid and its metabolites in rabbit plasma by high-performance liquid chromatography with fluorescence detection

A simple, accurate and sensitive high-performance liquid chromatographic method with fluorescence detection was used for measuring plasma concentrations of p-aminobenzoic acid (PABA) and its three metabolites: p-acetaminobenzoic acid (PAABA), p-aminohippuric acid (PAHA) and p-acetaminohippuric acid (PAAHA). A Cosmosil MS-C18 column (250 x 4.6 mm, 5 microns) was used under temperature control at 40 degrees C. The mobile phase was H2O-CH3CN-CH3COOH (100:3:1, pH 4.0) with a flow-rate of 1.5 ml/min. The excitation and emission wavelengths for fluorescence detection were set at 270 and 350 nm, respectively. Plasma samples (200 microliters) were acidified by the addition of 150 microliters of 1 m HClO4 solution containing salicylic acid (SA) as the internal standard. After centrifugation, 30 microliters of the supernatant were injected onto the column. Using this method, PABA and its three metabolites could be determined within 25 min. Within the investigated concentration ranges of PABA (0.1-50 micrograms/ml), PAABA (0.2-50 micrograms/ml), PAHA (0.1-50 micrograms/ml) and PAAHA (0.5-50 micrograms /ml), good linearity (r > 0.99) for the standard curves was obtained. The validation of this method showed coefficient of variance (C.V.) that was well below 15% for all compounds. After intravenous (i.v.) administration of PABA (20 mg/kg) to rabbits (n = 7), PABA followed a one-compartment open model elimination with a half-life of 10.90 +/- 1.03 min. The mean half lives for PAABA, PAHA and PAAHA were 24.61 +/- 6.42, 12.81 +/- 6.04 and 11.27 +/- 2.77 min, respectively.

Comparison of "inside-out" and "outside-in" interference screw fixation for anterior cruciate ligament surgery in a bovine knee

Despite numerous advances in graft fixation with anterior cruciate ligament (ACL) reconstruction, few studies have compared the fixation strength of interference screws placed "outside-in" and from "inside-out" techniques. To compare techniques, a bovine model was designed to fail at the femoral tunnel bone-screw interface. Twenty-four fresh bovine knees were stripped of all soft tissues except the ACL. The native ACL was loaded the failure at a strain rate of 50 cm/min with the knee flexed 45 degrees. One standardized femoral tunnel was created on all specimens. A 3/32-inch guide pin was drilled into the center of the ACL femoral origin and overreamed with an 11-mm reamer from inside-out until the lateral cortex was reamed. Consistently sized patellar bone blocks were created (8 x 5 x 25 mm) with an 8-mm tendon width. The bone blocks were randomized to an "inside-out" (group 1) and "outside-in" (group 2) technique. Bone blocks were secured with a 7 x 25 interference screw. Specimens were mounted with the femoral tunnel and bone block aligned parallel to the tensile force and strained to failure at 50 cm/min. Failure of the native bovine ACL occurred at a mean of 2,304 N (SD +/- 472 N; n = 24). The mode of failure for group 1 was 9 of 13 at the bone-screw interface and 4 of 13 interligamentous failures. The mode of failure for group 2 was 7 of 11 at the bone-screw interface, 3 of 11 interligamentous, and 1 bone block failure. The mean load to failure for group 1 was 1,151 N (SD +/- 320 N, n = 13) including the four ligamentous failures and 1,143 N (SD +/- 306 N, n = 9) excluding the ligamentous failures. The mean load to failure for group 2 was 1,017 N (SD +/- 262 N, n = 11), including all specimens and 843 N (SD +/- 262 N, n = 7) excluding the interligamentous and bone block failure specimens. The "inside-out" technique averaged 100 N greater fixation strength than the "outside-in" technique. Statistical analysis using two-sample Student's t-test showed no statistically significant differences between group 1 and group 2. Both techniques demonstrate comparable maximum load to failure in a bovine model tested at 50 cm/min.

Determination of caffeic acid in rabbit plasma by high-performance liquid chromatography

A simple and sensitive high-performance liquid chromatographic method involving UV detection was developed for determination of caffeic acid in rabbit plasma. A Lichrosphere CN column (250 mm x 4 mm I.D., 5 microns) was used as the stationary phase and the mobile phase consisted of 2% acetic acid solution at a flow-rate of 1.0 ml/min. The UV absorbance was monitored at 320 nm. The plasma sample was acidified by the addition of 0.01 parts of concentrated phosphoric acid (85%) to maintain caffeic acid stability. After a simple clean-up procedure, the limit of quantitation achieved was 0.1 micrograms/ml, and the standard curve was found to be linear over the concentration ranges of 0.1-2.0 micrograms/ml and 0.1-40 micrograms/ml. The coefficient of variation for within- and between-run precision and accuracy was less than 10%, and the recovery was 82.3%.

Instrumented laparoscopic spinal fusion. Preliminary Results

STUDY DESIGN

Seventeen consecutive patients underwent laparoscopic instrumented interbody fusions using custom-designed delivery instrumentation and "BAK" fusion cages; both are manufactured by Spinetech and the former was developed by the authors. The cases were performed at two spine centers under Food and Drug Administration investigational device evaluation clinical trials.

OBJECTIVES

We expect this approach will maintain a high fusion rate with diminished hospitalization time, recovery time, patient discomfort, and expense. The rehabilitative aspects of the procedure are a great improvement over traditional fusion approaches.

SUMMARY AND BACKGROUND DATA

Extraordinary advances in many endoscopic surgical fields have resulted in many endoscopic surgical fields have resulted in lowered morbidity, expense, and suffering associated with their open surgery counterparts. The authors have developed prototype of delivery instruments for the current laparoscopic fusion cage delivery system.

METHODS

The procedure is performed transperitoneally with carbon dioxide insufflation to enable video-assisted visualization through a 10-mm endoscope. Three 10-mm incisions and one 13- to 20-mm incision are required for one-level procedures. Two hollow titanium-threaded interbody implants are packed with autologous bone and inserted into the diseased interspace.

RESULTS

Seventeen patients, with an average follow-up period of 8 months and a range of 6-12 months, underwent the procedure. There were 14 single-level fusions and three two-level fusions, all involving L4-S1 levels. There were two cases that required conversion to open procedures without sequelae; two patients had remote donor site wound infections eradicated with incision and drainage and antibiotics, and one patient required subsequent posterior spinal decompression because of a displaced endplate fracture. Average hospital stay was an average of 2 days, excluding two patients with complications and very prolonged stay.

CONCLUSIONS

Although this procedure is associated with a long learning curve, the technique, once mastered, is effective and advantageous over current approaches to lumbar fusion. Operative time and hospital stay are expected to decrease with future instrumentation development and surgeon experience.