Dexamethasone treatment of tumor necrosis factor-alpha challenged organ of Corti explants activates nuclear factor kappa B signaling that induces changes in gene expression that favor hair cell survival

The objective was to determine the role of nuclear factor kappa B (NFκB) in dexamethasone base (DXMb) protection of auditory hair cells from tumor necrosis factor-alpha (TNFα)-induced loss on gene expression and cell signaling levels. Organ of Corti (OC) explants from 3-day-old rats were cultured under one of the following conditions: (1) media only--no treatment; (2) media+TNFα; (3) media+TNFα+DXMb; (4) media+TNFα+DXMb+NFκB-Inhibitor (NFκB-I); or (5) media+TNFα+DXMb+NFκBI-Scrambled control (NFκBI-C). A total of 60 organ of Corti explants (OC) were stained with FITC-Phalloidin after 96 h in culture (conditions 1-5) for hair cell counts and imaging of surface characteristics. A total of 108 OC were used for gene expression studies (i.e. B-actin, Bax, Bcl-2, Bcl-xl, and TNFR1) after 0, 24, or 48 h in vitro (conditions 1-4). A total of 86 OC were cultured (conditions 1-3) for 48 h, 36 of which were used for phosphorylated NFκB (p-NFκB) ELISA studies and 50 for whole mount anti-p-NFκB immunostain experiments. TNFα+DXMb exposed cultures demonstrated significant upregulation in anti-apoptotic Bcl-2 and Bcl-xl genes and downregulation in pro-apoptotic Bax gene expression; DXMb treatment of TNFα explants also lowered the Bax/Bcl-2 ratio and inhibited TNFR1 upregulation. After inhibiting NFκB activity with NFκB-I, the gene expression profile following TNFα+DXMb treatment now mimics that of TNFα-challenged OC explants. The levels of p-NFκB and the degree of nuclear translocation are significantly greater in TNFα+DXMb exposed OC explants than observed in the TNFα and control groups in the middle+basal turns of OC explants. These findings were supported by the results of the hair cell counts and the imaging results obtained from the whole mount OC specimens. DXMb protects against TNFα-induced apoptosis of auditory hair cells in vitro via activation of NFκB signaling in hair cell nuclei, and regulation of the expression levels of anti- and pro-apoptotic genes and a pro-inflammatory gene.

Prevalence and effectiveness of treatment of hypertension on cardiovascular morbidity and mortality in an elderly population aged 70 years and over

The prevalence of hypertension, effectiveness of blood pressure control and compliance, and the effectiveness of treatment on 18-month overall mortality and development of cardiovascular disease in an elderly Chinese population were studied. The study group examined were aged 70 years and over, and consisted of a random sample of subjects on the Old Age and Disability Allowance register. They were stratified by sex and 5-year age groups from 70-74 to 90+ years. Information obtained at baseline included medical history, use of drugs, and measurement of blood pressure. Subjects with a blood pressure > 160/90 were classified as hypertensive. The overall prevalence of hypertension was 48%, 19% being undiagnosed. Among subjects with a known history of hypertension and taking drugs, only approximately half had adequate control (BP < or = 160/90). One fifth of those with a known diagnosis of hypertension were not taking drugs. Subjects who developed stroke had a higher mean systolic and pulse pressure at baseline; no difference in mean pressures was observed for overall mortality or development of heart disease. No difference in mortality or development of cardiovascular disease was observed between the following groups: known history of hypertension and taking medication with controlled blood pressure, known history and taking medication and blood pressure poorly controlled or not taking drugs, and normal blood pressure with no history of hypertension.

Outbreak of hypoglycaemia: sexual enhancement products containing oral hypoglycaemic agent

OBJECTIVES

To describe a cluster of Hong Kong subjects with hypoglycaemia, after they had taken various non-prescription sildenafil products containing glibenclamide.

DESIGN

Retrospective study.

SETTING

A tertiary referral centre for clinical toxicology analysis in Hong Kong.

PATIENTS

All men referred to the laboratory for investigation of suspected drug-induced hypoglycaemia from December 2007 to September 2008.

MAIN OUTCOME MEASURES

The characteristics of these patients, including their clinical presentations, outcomes, drug history, urine toxicology analysis results, and in some instances, analysis results of unused products.

RESULTS

A total of 144 male patients were referred for suspected drug-induced hypoglycaemia. Sildenafil and glibenclamide, or their metabolites, were detected in the urine specimens of 68 (47%) patients, none of whom had been prescribed either drug by a registered medical practitioner. Among these subjects, 24 (35%) denied any use of sexual enhancement products despite repeated questioning. Eight patients had repeated exposure resulting in re-admission. The sources of these sexual enhancement products included pharmacies in Mainland China, friends, local pharmacies, peddlers, or were unknown. Three patients died, one remains in a vegetative state and one suffered cognitive impairment; the remaining 63 recovered fully. Twenty-five unused sexual enhancement products of seven different kinds were recovered for analysis. The median (range) of sildenafil and glibenclamide per unit dose was 64 (0.05-198) mg and 70 (0-158) mg, respectively.

CONCLUSION

These illegal products pose a severe and continued threat to society and therefore deserve widespread vigilance, so that such products can be eradicated at their source.

Characterization of contamination in and toxicities of a shipyard area in Hong Kong

This is the first integrated study on the contaminant characterization and toxicities of a shipyard area. This site in Hong Kong contained 3.6-33.4 mg kg(-1) dichlorodiphenyltrichloroethane and 5-79 g kg(-1) oil and grease. Other pollutants exceeding the Dutch intervention values were total polyaromatic hydrocarbons, total petroleum hydrocarbons, and metals Cu, Pb and Zn. These pollutants persisted partially owing to the poor fertility with <125 mg N kg(-1) and <530 mg P kg(-1) typical of coastal soil. Sediments collected within 100 m also showed contamination exceeding the China and Hong Kong intervention levels. The shipyard soil killed two bacteria Pseudomonas stutzeri and Acinetobacter sp. isolated from a clean coastal soil, inhibited germination of three exogenous plants Triticum aestivum, Brassica chinense and Lolium perenne, and inhibited proliferation of three indigenous bacteria: Methylobacterium sp., Pseudomonas aeruginosa and Bacillus cereus. Thus, ex situ remediation was needed.

Data management using the personal digital assistant in an acute pain service

Handheld personal digital assistants (PDA) are increasingly being used by physicians for a variety of information and data management purposes. We evaluated a PDA-based data management system for our acute pain service. A structured questionnaire survey was conducted to assess staff experience and attitude towards the paper system before the introduction of the PDA, and three months after introduction of the PDA system. We compared the time taken to conduct the acute pain round before and after the implementation of the PDA. The time saved in data management and the amount of paper saved were estimated. Data from 177 patients with a total of 635 acute pain follow-up visits were entered over a three-month period. User satisfaction, ease of access to drug reference and clinical guidelines were similar between the two systems. The respondents found that the PDA was easy to use but less so than the paper system (P = 0.007), in particular, when accessing a patient's cumulative data (P = 0.007). There was no missed follow-up or data entry with the use of PDA. The time taken to attend follow-up visits was similar for the two systems (Paper: 8.8 +/- 3.2 compared to PDA: 7.0 +/- 2.0 minutes, P = 0.151). The estimated annual amount of paper and time saved in data management was 650 sheets and 130 man-hours respectively. Our experience with the use of the PDA in APS was satisfactory. The PDA system can potentially reduce time and paper use and missed data entry and patient follow-up.

Separation of 100-kilobase DNA molecules in 10 seconds

Long double-stranded DNA molecules were separated in microfabricated hexagonal arrays in less than 1 min, several orders of magnitude faster than by using conventional technology. DNA samples were first concentrated at the entrance to the array in a thin band by entropic focusing. They were then separated by pulsed field electrophoresis. T4 (168.9 kbp) and lambda (48.5 kbp) DNAs could be resolved into two clearly separated bands in approximately 10 s in these experiments. This corresponds to a mass resolution of 6% in 11 min in a 1-cm-long array.

Alpha-tocopherol modulates tyrosine phosphorylation in human neutrophils by inhibition of protein kinase C activity and activation of tyrosine phosphatases

Alpha-tocopherol augmentation in human neutrophils was investigated for effects on neutrophil activation and tyrosine phosphorylation of proteins, through its modulation of protein kinase C (PKC) and tyrosine phosphatase activities. Incubation of neutrophils with alpha-tocopherol succinate (TS) resulted in a dose-dependent incorporation into cell membranes, up to 2.5 nmol/2x10(6) cells. A saturating dose of TS (40 micromol/l) inhibited oxidant production by neutrophils stimulated with phorbol myristate acetate (PMA) or opsonized zymosan (OZ) by 86 and 57%, as measured by luminol-amplified chemiluminescence (CL). With PMA, TS inhibited CL generation to a similar extent to staurosporine (10 nmol/l) or genistein (100 micromol/l), and much more than Trolox (40 micromol/l). With OZ, TS inhibited CL to a similar extent to Trolox. Neutrophil PKC activity was inhibited 50% or more by TS or staurosporine. The enzyme activity was unaffected by genistein or Trolox, indicating a specific interaction of alpha-tocopherol. TS or Trolox increased protein tyrosine phosphorylation in resting neutrophils, and as with staurosporine further increased tyrosine phosphorylation in PMA-stimulated neutrophils, while the tyrosine kinase (TK) inhibitor genistein diminished phosphorylation. These effects in resting or PMA-stimulated neutrophils were unrelated to protein tyrosine phosphatase (PTP) activities, which were maintained or increased by TS or Trolox. In OZ-stimulated neutrophils, on the other hand, all four compounds inhibited the increase in tyrosine-phosphorylated proteins. In this case, the effects of pre-incubation with TS or Trolox corresponded with partial inhibition of the marked (85%) decrease in PTP activity induced by OZ. These results indicate that alpha-tocopherol inhibits PMA-activation of human neutrophils by inhibition of PKC activity, and inhibits tyrosine phosphorylation and activation of OZ-stimulated neutrophils also through inhibition of phosphatase inactivation.

Community-acquired pneumonia--implementation of a prediction rule to guide selection of patients for outpatient treatment

The aim of this study was to determine the outcomes of outpatient treatment of community-acquired pneumonia (CAP) when a prediction rule was followed by emergency physicians to guide the selection of patients. This was a prospective observational study conducted at the emergency department of a university-affiliated hospital in Hong Kong, China. A clinical prediction rule was implemented to guide the selection of patients with CAP for outpatient treatment. All subsequent hospitalizations gial presentation were recorded, and the reasons were assessed. The utilization of the observation unit was incorporated into the treatment algorithm. Of 72 patients with CAP followed up as outpatients, 60 (83.3%) were treated successfully, nine (12.5%) required subsequent hospitalization within 30 days, and three (4.2%) were lost to follow-up. None of the patients died, and none required admission to the intensive care unit. Factors associated with subsequent hospitalization include: tuberculosis, underlying malignancy, persistent fever, comorbidity (rheumatoid arthritis and severe osteoporosis), intravenous drug addiction and alcoholism. The observation ward was utilized in 10 (16.7%) patients successfully treated as outpatients. It is concluded that the prediction rule can be safely implemented as a guide for emergency physicians. The short-stay observation unit may be usefully employed for treating low-risk CAP.

Using conjoint analysis to assess patients' preferences when visiting emergency departments in Hong Kong

OBJECTIVES

To explore factors related to emergency department (ED) attendances in Hong Kong, the authors piloted the application of conjoint analysis in eliciting patient preferences regarding ED visits.

METHODS

The study recruited 390 semi-urgent or non-urgent patients from a targeted convenience sample of three large EDs. Respondents were asked to rank eight scenarios structured to explore the relative importance of three key attributes-self-perceived illness severity, waiting time, and consultation fee-that may result in an ED visit.

RESULTS

Seventy-eight percent of the respondents would consider visiting a parallel clinic instead of the ED for semi-urgent and non-urgent conditions. The relative importance attached to illness severity, waiting time, and consultation fee were 47.8%, 33.6%, and 18.7%, respectively.

CONCLUSIONS

This study demonstrated that Hong Kong patients are receptive to the concept of parallel clinics, and illustrated that conjoint analysis is a rigorous survey technique for eliciting the views of patients on health care services in the ED setting.

A sensitive assay for the measurement of serum chondroitin sulfate 3B3(-) epitope levels in human rheumatic diseases

OBJECTIVE

To develop a sensitive assay to quantitate serum 3B3(-) levels in patients with rheumatoid arthritis (RA) and osteoarthritis (OA) as well as levels in control sera.

METHODS

An enzyme-linked immunosorbent assay (ELISA) was developed using the monoclonal antibody (MAb) 3B3 to detect a chondroitin sulfate (CS) epitope in the sera and synovial fluid (SF) of RA and OA patients. Keratan sulfate levels were measured in the same biological fluids using the 5D4 monoclonal antibody.

RESULTS

The detection limit for our 3B3(-) assay was 2 micrograms/L. Most OA sera sample curves run on the 3B3 assay were parallel (87.5%) to the standard curve and detectable (90.0%). RA sera sample curves were 87.1% detectable and 85.2% parallel. The 3B3(-) epitope was detectable in 60% of control sera and of these 66.7% of sample curves were parallel to the standard curve. All RA and OA SF had detectable quantities of 3B3(-). For the 3B3 assay, the OA and RA sera levels were significantly higher than for control sera (P = 0.03, P = 0.04 respectively). We found a significant correlation in a subset of paired OA sera and SF 3B3(-) concentrations. No correlation was found between age, joint activity scores, HAQ and CRP in RA patients and sera 3B3(-) and 5D4 levels.

CONCLUSION

We have validated this assay for the quantification of 3B3(-) epitope in RA and OA serum. Levels of this epitope are significantly higher in sera from RA and OA patients than controls. 3B3(-) levels in RA sera were found to correlate with disease duration.

Epidemiology of health changes in older women in Hong Kong

This paper aims to present the baseline social, mental and functional characteristics, the changes of these characteristics over a 36-month follow-up period, and the issues and implications related to these changes, particularly in older women. The cohort comprising 2030 subjects aged 70 and above has been assembled by stratified disproportional random sampling. Registrants with the Old Age Allowance Scheme, which has over 90 percent coverage of the Hong Kong elderly population, was used to define the accessible population. Face-to-face interviews were conducted at the respondents' place of residence. A number of social and health variables were collected at baseline. The surviving subjects had been followed up at 36 months and repeated measurements of the baseline variables were obtained. Older women were over-represented by low level education, financial dependency, as well as residence in institutions. Women had higher prevalence as well as incidence of musculoskeletal problems. While there was a general decline in health and social support in the elderly cohort, we observed a preponderance of older female subjects with mental and functional decline over the follow-up period. An overrepresentation of female subjects with depressive symptoms at baseline and follow-up was also noted. The descriptive data have revealed a host of social and health changes over a three-year follow-up period. Women aged 80 years and above formed a particularly disadvantaged group. The results will have direct implications for the shaping of social and health policy for strategic planning of priorities in social and health care services.

Near-field scanner for moving molecules

We have fabricated using electron beam nanolithography a fixed slit near-field optical scanning device which uses near-field fluorimetry to achieve 200 nm spatial resolution of objects moving over the slits. We explore the basic physics of operating narrow slits in the waveguide cutoff mode and present data from the passage of extended double-stranded DNA molecules passing over the slits as a first example of how this device can be used to do ultrahigh spatial resolution mapping of long polymers.

Current opinions and practices in the treatment of spontaneous pneumothorax

The approach to the initial management of spontaneous pneumothorax differs markedly from centre to centre, and it is difficult in practice to establish a standard protocol. This article reviews the concepts behind the British Thoracic Society guidelines, and reports the varying opinions and alternative practices existing currently. There is a need for more evidence-based studies to identify what is the best approach. Based on a review of relevant recent reports, the author attempts to work out an unbiased practical approach that can be used safely and that can possibly give the best overall cost effective results.

Sorting biomolecules with microdevices

Micro- and nanofabrication techniques have provided an unprecedented opportunity to create a designed world in which separation and fractionation technologies which normally occur on the macroscopic scale can be optimized by designing structures which utilize the basic physics of the process, or new processes can be realized by building structures which normally do not exist without external design. Since microfabrication is exceedingly sophisticated in its development, it is possible to design and construct highly creative microdevices which allow one to probe specific aspects of biological objects. We give examples of uses of micro- and nanofabrication which, as opposed to simply shrinking the size of the vessels or tubes used in macroscopic lab environments, utilize our understanding of the physics of the process to take advantage of fabrication technologies.

Reevaluation of the determinants of tyrosine sulfation

The posttranslational sulfation of tyrosine has been thought to be initiated by the recognition of specific consensus features by the sulfating enzyme tyrosylprotein sulfotransferase (TPST). However, using these recognition features to identify new tyrosine sulfation sites misses recently characterized sites that lack these features. Rigorous analysis of the amino acids surrounding the target tyrosine using the position-specific scoring matrix (PSSM) demonstrates that a consensus sequence does not contain all the information necessary to predict tyrosine sulfation. Instead, accurate prediction requires consideration of all residues within five amino acids on either side of the target tyrosine. These results support the notion that secondary structure is the major determinant of sulfation and that other residues within the sulfation site can compensate for deviations from commonly observed features. This view implies that specific consensus features are not critical for TPST substrate recognition but that TPST may instead broadly recognize any sufficiently exposed tyrosine residue.

Sorting by diffusion: an asymmetric obstacle course for continuous molecular separation

A separation technique employing a microfabricated sieve has been demonstrated by observing the motion of DNA molecules of different size. The sieve consists of a two-dimensional lattice of obstacles whose asymmetric disposition rectifies the Brownian motion of molecules driven through the device, causing them to follow paths that depend on their diffusion coefficient. A nominal 6% resolution by length of DNA molecules in the size range 15-30 kbp may be achieved in a 4-inch (10-cm) silicon wafer. The advantage of this method is that samples can be loaded and sorted continuously, in contrast to the batch mode commonly used in gel electrophoresis.

Passive smoking exposure of sick children in Hong Kong

1. This study aims to investigate the extent of passive smoking exposure of sick children in Hong Kong; their father's smoking behaviors and their mother's action to protect the child from environmental tobacco smoke (ETS). 2. This cross-sectional survey was the first phase of a randomized controlled trial on a health education intervention provided by nurses in the general paediatric wards of four major hospitals in Hong Kong. The subjects are non-smoking mothers of sick children admitted to hospital and with a smoking husband living together in the same household with the child. Eligible subjects completed a self-administered baseline questionnaire before entering into the trial. 3. All the 848 children whose mothers completed the questionnaire during December 1997 to April 1998 had a smoking father. They constituted about 24% (95% CI: 22.6-24.9%) of all the sick children during the same period. More than half of the children's fathers (55%; 51.6-58.3%) smoked 1-14 cigarettes per day and about 68% (64.7-71.0%) of them were daily smokers for over 10 years. Over half (53%; 49.4-56.2%) of the fathers smoked 1-14 cigarettes at home every day. About 21% of the fathers smoked near the child occasionally and 31% (27.4-33.6%) smoked 1-14 cigarettes near the child per day. About 16% of the children lived with more than one smoker (2-3). About 86% (83.3-88.0%) of the children had 1-3 smokers who smoked at home and 61% (58.1 - 64.7%) of them had 1-3 smokers who smoked near them every day. However, 70% of the children were reported by their mothers as exposed to ETS at home. This percentage (70%) was less than the percentage (86%) of smokers who smoked at home daily. About 31.1% of the mothers reported symptoms of coughing and running nose (20.6%) in their children when they were exposed to ETS. To protect the child from ETS exposure, 43% of the mothers requested the father not to smoke near the child, 33.1% requested the father to smoke less cigarettes and 31.5% advised the father to quit smoking. 4. In conclusion, sick children in Hong Kong are at risk of exposure to ETS, but not all mothers are aware of the health risks and their actions were inadequate. There is a critical need to promote awareness of ETS exposure and the health risks in the family in Hong Kong so as to reduce illness and hospital admission in children.

Functional activity of blood polymorphonuclear leukocytes as an oxidative stress biomarker in human subjects

In the present work, we studied the role of polymorphonuclear leukocytes (PMN) in aged individuals and coronary heart disease (CHD)-bearing patients, two physiopathological processes associated with overproduction of reactive oxygen species (ROS). The effects of antioxidant supplementation on the functional activity of PMN from CHD patients were also determined. The function of PMNs was evaluated by measuring of phagocytosis, killing activity, and ROS production. Luminol amplified chemiluminescence (CL) was used to estimate ROS production by stimulated PMNs. Total cholesterol and the LDL-cholesterol fraction from CHD patients were found to be higher than those recommended, returning to normal levels after antioxidant therapy. PMN CL of CHD patients was found to be higher than the associated control groups. Antioxidant therapy administrated to CHD patients lead to an increase in the killing activity accompanied by a decrease in PMN CL of these subjects. The study also showed that killing activity of PMN from human subjects over 60 years was significantly lower than the activity measured in younger subjects. PMN CL produced after stimulation was found to be positively correlated with the increasing age of human subjects (r=.946, p < .01).

The effects of multiple-strand suture methods on the strength and excursion of repaired intrasynovial flexor tendons: a biomechanical study in dogs

This study was designed to determine the effects of in vivo multistrand, multigrasp suture techniques on the strength and gliding of repaired intrasynovial tendons when controlled passive motion rehabilitation was used. Twenty-four adult mongrel dogs were divided into 4 groups and their medial and lateral forepaw flexor tendons were transsected and sutured by either the Savage, the Tajima, the Kessler, or the recently developed 8-strand suture method. The tendon excursion, joint rotation, and tensile properties of the repaired tendons were evaluated biomechanically at 3 and 6 weeks after surgery. It was found that neither time nor suture method significantly effected proximal and distal interphalangeal joint rotation or tendon excursion when the 4 techniques were compared to each other. Normalized load value (experimental/control) was significantly affected by both the suture method and the amount of time after surgery, however. The Savage and 8-strand repair methods had significantly greater strength than did the Tajima method at each time interval (p < .05 for each comparison). In addition, the 8-strand method had significantly greater normalized load values than did the Savage method at each time interval (p < .05 for each comparison). Normalized stiffness (experimental/control) for the 8-strand repair method was significantly greater than that for the Tajima and Savage methods at 3 and 6 weeks after surgery (p < .05). In addition, the normalized stiffness values for the 6-week groups was significantly greater than those for the 3-week groups (p < .05). It was concluded that the method of tendon suture was a significant variable insofar as the regaining of tendon strength was concerned and that the newer low-profile 8-strand repair method significantly expands the safety zone for the application of increased in vivo load during the early stages of rehabilitation.

Identification and characterization of growth hormone receptors in snakehead fish (Ophiocephalus argus cantor) liver

The specific binding of 125I-labeled fish growth hormone (GH) to hepatic membranes prepared from several freshwater fish was assessed. A high level of growth hormone receptor (GHR) was detected on the hepatic membranes of the snakehead fish (Ophiocephalus argus Cantor). Scatchard analysis of the binding data showed a single class of high affinity binding site with a binding affinity (Ka) of 1.45 +/- 0.23 x 10(9) M-1 and a binding capacity (Bmax) of 198 +/- 57 fmol/mg protein. The binding was specific for fish GH and was saturable. In addition, the specific binding was temperature- and time-dependent, reaching a steady state after 16 hr of incubation at 25 degrees . The molecular weight of GHR as measured by Sephadex G-200 column chromatography and Western blot analysis using a monoclonal antibody (Mab263) against GHR was found to be 200-400 and 90-93 kDa, respectively. Two bands at 65 and 89 kDa were identified in ligand crosslinking studies of membrane receptors. A sensitive teleost GH radioreceptor assay (RRA) was developed, using recombinant fish GH and a membrane preparation from snakehead fish liver, capable of measuring bioactive GH in fish sera or other samples.

Motor power pharmacodynamics of subarachnoid hyperbaric 5% lidocaine in the sitting position

BACKGROUND

Repetitive dynamometric measurement using a plantar flexion power device (PFPD) provides detailed data describing the onset and offset of motor block following spinal administration of lidocaine. The aim of this study was to evaluate administration of two doses of spinal lidocaine in the sitting position to determine whether our dynamometric model produces data consistent with our current understanding of the pharmacokinetics of subarachnoid, hyperbaric, 5% lidocaine.

METHODS

Twenty male patients (54 to 80 yr) undergoing cystoscopy received spinal anaesthesia with either 75 mg (n = 10) or 100 mg of hyperbaric lidocaine 5%, in the sitting position, under standardised conditions. Plantar flexion muscle power was recorded during onset and offset of anaesthesia using a load cell interfaced with a computer (PFPD).

RESULTS

Onset of paralysis following spinal block in the sitting position was rapid and complete with motor power declining exponentially to 5% of preoperative values by 8.5 min in all patients. There was no difference in decay or recovery of plantar flexion motor power data between dosage groups in the sitting position. Measurement using the PFPD shows that onset of motor paralysis is described by an exponential decay and that motor recovery occurs at a fixed rate. Extent of block to cold and pinprick was similar in both dosage groups in the sitting position (median T4).

CONCLUSION

This study shows that in the sitting position, doses less than 75 mg of 5% hyperbaric lidocaine are required to significantly improve ambulatory times.

Biomechanics of knee ligament healing, repair and reconstruction

Injuries of the anterior cruciate ligament (ACL) and the medial collateral ligament (MCL) are common, accounting for 90% of all knee ligament injuries in young and active individuals. During the last decade, our research center has focused on MCL healing and ACL reconstruction. We have found that the MCL heals without intervention after an isolated injury, and that primary repair offers no apparent advantage. After a combined injury of the ACL and MCL, the ACL requires reconstruction, whereas primary repair again contributes little or nothing toward MCL healing. Midsubstance ACL injuries have limited healing ability. Hence, the treatment of choice for a torn ACL in a young, active patient is generally reconstruction with an autograft or allograft. However, the appropriate replacement graft and reconstruction technique to use are still debated. Current research efforts have been placed on investigating the magnitude and direction of in situ forces in the human ACL. We use a six-component universal force moment sensor combined with a six-degree-of-freedom (DOF) robotic manipulator to learn as well as to reproduce the six-DOF motion of the knee before and after ACL injury. This way, the in situ force in the ACL under an anterior posterior tibial load of 110 N was obtained. This methodology should make it possible to obtain the needed data to aid in better understanding of ACL reconstruction and possible development of improved clinical management.

Temperature-dependent ultraviolet resonance Raman spectroscopy of the premelting state of dA.dT DNA

Poly(dA).poly(dT) and DNA duplex with four or more adenine bases in a row exhibits a broad, solid-state structural premelting transition at about 35 degrees C. The low-temperature structure is correlated with the phenomena of "bent DNA." We have conducted temperature-dependent ultraviolet resonance Raman measurements of the structural transition using poly(dA).poly(dT) at physiological salt conditions, and are able to identify, between the high and low temperature limits, changes in the vibrational frequencies associated with the C4 carbonyl stretching mode in the thymine ring and the N6 scissors mode of the amine in the adenine ring of poly(dA).poly(dT). This work supports the model that the oligo-dA tracts' solid-state structural premelting transition is due to a set of cross-stand bifurcated hydrogen bonds between consecutive dA. dT pairs.