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Biomedical subjects

R C Watson

Publications and source records attributed to R C Watson.

At least 19 recordsLinked to original sources
PubMed2001

Effects of acid treatment on the trace metal content of chromatographic silica: bulk analysis, surface analysis and chromatographic performance of bonded phases.

A series of studies has been carried out on the effect of refluxing silica chromatography particles for 0.5 h and 18 h in water, dilute hydrochloric acid and dilute hydrofluoric acid. The bulk and surface trace metal concentrations were measured by inductively-coupled plasma atomic emission spectroscopy, static secondary ion mass spectrometry (SSIMS) and X-ray photoelectron spectroscopy. Diffuse reflectance Fourier transform infrared spectroscopy was used to determine changes in 'isolated" and "bonded" silanol groups. The chromatographic behaviour of a series of weakly basic analytes was investigated on C8 and C18 bonded phases manufactured from the acid-treated silicas. The different reflux treatments all resulted in a reduction in the numbers of isolated silanols compared with the untreated silica and SSIMS analysis suggested that the HF-treated silicas had undergone a more efficient surface rehydroxylation. Bulk trace metals were removed most effectively by the HF treatment, with the multivalent elements (Ti and Al) being the most difficult to remove. Surface specific analysis suggested that trace metals were removed more rapidly from the surface of the silica compared to the bulk matrix and that the acid treatments resulted in halide contamination of the silica surface. Evidence is presented to suggest that the bulk metal content of the silica is not representative of the concentration of metals at the chromatographic surface. The chromatographic investigations showed that the HF-treated silica gave substantially better performance towards weak bases than the HCl-treated silicas.

Acids↗
PubMed2001

Characterization of inorganic coordination complexes by matrix-assisted laser desorption/ionization mass spectrometry.

We report the direct laser desorption/ionization (LDI) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometric (MALDI-TOFMS) analysis of four inorganic coordination complexes: monometallic [Ir(dpp)(2)Cl(2)](PF(6)), homonuclear trimetallic ([(bpy)(2)Ru(dpp)](2)RuCl(2))- (PF(6))(4), and heteronuclear [(tpy)Ru(tpp)Ru(tpp)RhCl(3)](PF(6))(4) and ([(bpy)(2)Ru(dpp)](2)IrCl(2))(PF(6))(5) (dpp = 2,3-bis-(2'-pyridyl)pyrazine, bpy = 2,2'-bipyridine, tpy = 2,2',6',2"-terpyradine, tpp = 2,3,5,6,-tetrakis-(2'-pyridyl)pyrazine). Spectral intensities and fragmentation patterns are compared and evaluated for instrument parameters, matrix selection, and matrix-to-analyte ratio. Direct LDI and MALDI mass spectra of the monometallic complex showed the same ion peaks and differed only in the relative peak intensities. Direct LDI of the trimetallic complexes produced only low-mass fragments containing one metal at most. MALDI spectra of the trimetallic complexes exhibited little fragmentation in the high-mass region (>1500 Da) and less fragmentation in the low-mass region compared to direct LDI. Significant fragments of the molecules were detected and identified, including ligand fragments, intermediate-mass fragments such as [Ru(tpy)](+), and molecular ions with varying degrees of PF(6)(-) loss ([M - n(PF(6))](+), where n = 1-3). A correlation exists between the solution-phase electrochemistry and the observed [M - n(PF(6))](+) series of peaks for the trimetallic complexes. Proper matrix selection for MALDI analysis was vital, as was an appropriate matrix-to-analyte ratio. The results demonstrate the applicability of MALDI-TOFMS for the structural characterization of labile inorganic coordination complexes.

Journal Article↗
PubMed1997

Safety in Canadian junior ice hockey: the association between ice surface size and injuries and aggressive penalties in the Ontario Hockey League.

OBJECTIVE: To investigate the associations between ice surface size and injuries and aggressive penalties in Canadian junior hockey. DESIGN: Injury (all injuries and neurotraumas) and penalty data (aggressive and nonaggressive) were categorized into the ice surface size on which they occurred: larger than standard (LTS), standard (S), and smaller than standard (STS). PARTICIPANTS: There were 328 injury records and 538 penalty records collected for all 16 teams in the Ontario Hockey League (OHL) during the 1993-94 season. The OHL is a junior A league comprised of amateur players aged approximately 16-20 years. MAIN OUTCOME MEASURE: In the absence of any evidence, the null hypotheses of no association between injuries and ice surface size and penalties and ice surface size were tested. RESULTS: The rates of injury per game were inversely related to ice surface sizes (95% confidence intervals: LTS, 0.33 +/- 0.20; S: 0.58 +/- 0.08; and STS, 0.76 +/- 0.06). The associations for all of the paired comparisons of these rates with ice surface size were statistically significant (p < 0.01). Neurotraumas per game and aggressive penalty rates showed no significant relationship with ice surface size (p < 0.05). CONCLUSIONS: It was concluded that ice surface size is a risk factor to consider in assessing overall injury rate. The larger the ice surface is, the lower is the rate of injury. It appears that the medical community was correct in suspecting ice surface size as a factor in creating a safer environment for ice hockey players. Penalty data do not appear to be important factors in relation to ice surface size.

Adolescent↗
PubMed1996

Checking from behind in ice hockey: a study of injury and penalty data in the Ontario University Athletic Association Hockey League.

OBJECTIVE: In this study we investigated the association between the introduction of the checking-from-behind rule (CFB) in the Ontario University Athletic Association (OUAA) hockey league and player safety. DESIGN: Injury and penalty data were collected for the 3 years prior to and the 3 years following the introduction of the CFB rule in 1989. PARTICIPANTS: There were 653 injury records and 389 penalty records for 3 OUAA teams that had complete records for the 6 years. MAIN OUTCOME MEASURE: In the absence of any a priori evidence, the null hypotheses of no association between the CFB rule and injuries or penalties, apart from a logical assumption that there would be a pre-/post difference in CFB penalties, were tested. RESULTS: Although the injury rates for each of the body segments (heat/neck, back, shoulder) demonstrated a significant independence (chi 2 = 56.66, df = 2, p < 0.001) from each other in relation to the pre-/post rule period, only the CFB penalty rates exhibited significant independence (chi 2 = 16.58, df = 2, p < 0.001) from body contact and stick-related penalties. CONCLUSIONS: These findings suggest that the introduction of the CFB rule was related to a safer playing environment as reflected by a pre-/post rule decrease in two of three categories of injury, increased CFB penalty rates, and the absence of significant association between the CFB rule and the decreases in body contact penalties and stick-related infractions. It appears that the medical community, with the supporting clinical data demonstrating CFB-related injuries, has helped create enhanced safety without significantly changing player behavior.

Athletic Injuries↗
PubMed1992

Treatment of unstable tibial shaft fractures by closed intramedullary nailing with flexible (Ender-type) pins.

Eighty patients with unstable tibial diaphyseal fractures were treated by closed intramedullary nailing with Ender-type flexible pins. The majority of injuries occurred from falling while snow skiing. Sixty-six fractures were closed and 14 were open. Fifty-eight fractures involved the distal, 21 fractures the middle, and one fracture the proximal one third of the tibial shaft. The average time to roentgenographic union was 15.5 weeks (range, ten to 34 weeks) for closed and open Grade I and II fractures. The time to union in Grade III fractures was 50 weeks (range, 36-64 weeks). There were two nonunions and two delayed unions. Both nonunions occurred in Grade IIIA open shaft fractures. Intramedullary stabilization with flexible, Ender-type pins provides good control of unstable tibial shaft fractures. The use of pins with a smaller diameter (3.5 or 4 mm) allows the surgeon to place more pins across the fracture site. The use of multiple pins and packing the intramedullary canal may provide better rotational stability. The use of Ender-type pins for fixation of Type IIIA open tibial shaft fractures is contraindicated.

Adolescent↗
PubMed1989

Methotrexate, vinblastine, doxorubicin, and cisplatin for advanced transitional cell carcinoma of the urothelium. Efficacy and patterns of response and relapse.

Of 133 patients with advanced urothelial tract cancer given methotrexate (MTX), vinblastine (VBL), Adriamycin (ADR) (doxorubicin; Adria Laboratories, Columbus, OH), and cisplatin (DDP) (M-VAC regimen), significant tumor regression occurred in 72% +/- 8% of 121 with transitional cell carcinoma (TCC) evaluable for response. Complete remission (CR) was achieved in 36% +/- 9% of patients, of whom 11% required the addition of surgical resection of residual disease. Although 68% of CR patients have relapsed, CR median survival will exceed 38 months compared with 11 months for partial (36%) and minor (6%) responders, and 8 months for nonresponders: 2-year and 3-year survivals were 68% and 55%, respectively, versus 0% to 7% for the remaining patients. Sixteen percent of responders developed brain lesions, half of whom had no systemic relapse at the time of progression. Three patients with non-TCC histologies did not respond. In 32 patients who had pathologic restaging, the clinical (T) understaging (T less than pathologic [P] restaging) error was 35%. Although all metastatic sites showed evidence of tumor regression, CR was noted more frequently in lung, in intraabdominal lymph nodes and masses, and in bone (24% to 35%); the rate for hepatic lesions was 15%. There were 52% of 21 N3-4M0 patients who achieved CR versus 33% of 100 with N0-+M+ lesions. Toxicity was significant with 4 (3%) drug-related deaths, 25% incidence of nadir sepsis, 58% greater than or equal to 3+ myelosuppression, and 49% with mucositis. Responsiveness of metastasis in various sites, patterns of relapse, and the usefulness of the new CR response criteria are reported, as is the current status of cisplatin and methotrexate combination regimens.

Adult↗
PubMed1989

Where antecubital catheters go: a study under fluoroscopic control.

Fifty attempted central venous cannulations via the antecubital route were studied with fluoroscopy to determine catheter tip location. Only "catheter through needle" devices were employed. Successful central placement occurred on the first attempt in 27 cases. The major impediment to central location of the catheter tip (ten cases) was the tendency of the catheter tip to lodge at the subclavian-internal jugular vein junction. The second most common cause of noncentral location was migration of the catheter tip into the internal jugular vein (nine cases). One catheter tip was located in the contralateral subclavian vein and one ended in the external jugular vein. All of these problems were avoided by two maneuvers: 1) turning the patient's head toward the side of cannulation and applying digital pressure to the ipsilateral supraclavicular fossa, and 2) withdrawing the catheter stylet and injecting 5-10 ml of physiologic saline solution while the catheter was advanced. The only cause of unsuccessful central placement in this study was inability to pass the catheter tip past the axillary venous plexus (two patients). It is concluded that the head-turn-supraclavicular fossa pressure maneuver in combination with the stylet withdrawal-saline injection maneuver can result in greater than a 90% rate of successful central venous catheter placement.

Axillary Vein↗
PubMed1989

Compartment syndrome. A complication of intravenous regional anesthesia in the reduction of lower leg shaft fractures.

Forty-one consecutive patients who had closed reduction of closed lower leg shaft fractures under an intravenous regional anesthetic are reviewed for the complication of compartment syndrome. Four patients were graded as having mild compartment syndrome, two as moderate, and five as severe, giving an overall rate of 27%. This was compared with a control group of 39 consecutive patients who also underwent closed reduction of closed lower leg shaft fractures, but under general anesthesia or intravenous analgesia alone rather than an intravenous regional anesthetic. In the control group, three patients were graded as having mild compartment syndrome, and two as severe, giving an overall complication rate of 13%. The authors feel that the use of the thigh tourniquet with the intravenous regional anesthetic technique increases the frequency of compartment syndrome as a complication in lower leg fractures.

Anesthesia, Conduction↗
PubMed1988

Primary tumors and tumor-like lesions of the clavicle.

Fifty eight patients seen at Memorial Sloan-Kettering Cancer Center over a 50-year period were reviewed for lesions of the clavicle. A variety of malignant neoplasms, benign neoplasms, and tumor-like lesions were seen. There were 30 malignant neoplasms, the commonest of which were plasmacytomas, osteosarcomas, and Ewing sarcomas. There were five postradiation sarcomas. An unusual granulocytic sarcoma with dense sclerosis was described. Among the benign lesions were two osteochondromas, two hemangiomas, and a giant cell tumor secondary to Paget disease. The tumor-like lesions included six aneurysmal bone cysts and five eosinophilic granulomas. There were two patients with chronic sclerosing osteomyelitis and one each with sternocostoclavicular hyperostosis (Sonozaki syndrome) and condensing osteitis. An unusually large lesion of pseudogout and a large brown tumor were also included in the series.

Adolescent↗
PubMed1988

M-VAC (methotrexate, vinblastine, doxorubicin and cisplatin) for advanced transitional cell carcinoma of the urothelium.

Of 92 patients who received methotrexate, vinblastine, doxorubicin and cisplatin complete and partial remissions were observed in 69 +/- 10 per cent of 83 adequately treated measurable and evaluable patients with advanced stages (N+M0 and N0M+) transitional cell urothelial cancer. Complete remission was achieved in 37 +/- 10 per cent of the patients clinically, pathologically and after surgical resection of residual disease. With 17 of 31 complete responders (55 per cent) surviving for 26+ to 49+ months, the estimated probability of survival at 2 and 3 years was 71 and 55 per cent, respectively. Partial remission occurred in 31 +/- 10 per cent of the patients, while 8 per cent had a minor response and 23 per cent had progression with median survivals of 11, 11 and 7 months, respectively. Whereas all metastatic sites responded, including the bone and liver, complete tumor regression was observed more frequently with nodal, pulmonary and local-regional lesions. Brain metastases occurred within 6 to 42 months in 18 per cent of the responders, half of whom never had systemic relapse. Of the remaining 9 patients 2 with nontransitional cell histological tumors did not respond, 5 (5 per cent) were inadequately treated and 2 were excluded from response data because of inevaluable disease parameters but they were free of disease at 16+ and 31+ months. Toxicity was significant, with 20 per cent of the patients experiencing nadir sepsis, 4 per cent a drug-related death, 31 per cent +1 renal toxicity and 41 per cent +1 mucositis. The applications and advantages of the newly proposed international response criteria for bladder cancer are discussed in reference to 25 patients who underwent surgical re-staging, indicating that the disease was understaged clinically in 24 per cent (T less than P), as well as in reference to attainment of true (pathological) complete remission and to other urothelial tract trials. While this therapy seems to have limited antitumor activity against nontransitional cell histological cancer, stage Tis disease and later development of de novo lesions, the regimen is efficacious in selected patients with advanced urothelial tract transitional cell carcinoma.

Adult↗
PubMed1988

Neoadjuvant M-VAC (methotrexate, vinblastine, doxorubicin and cisplatin) effect on the primary bladder lesion.

Of 50 patients with bladder cancer given 1 to 5 cycles of neoadjuvant methotrexate, vinblastine, doxorubicin and cisplatin in a pilot phase I and II study 63 per cent of 41 with pure transitional cell stage T2-4 lesions responded. While significant downstaging occurred by transurethral resection of the bladder in 70 per cent and by cytology in 60 per cent of the patients, the final T response rate by all noninvasive clinical staging procedures, including sonography and computerized tomography, revealed complete remission in 24 per cent and partial remission in 39 per cent. Of 30 patients who underwent pathological staging 33 per cent achieved stage P0 and 17 per cent stage Tis disease or P less than T. Despite extensive re-evaluation by transurethral resection of the bladder and other noninvasive staging procedures, a clinical staging error (T versus P) of 38 per cent was observed. Of the other 9 patients 4 with mixed nontransitional cell histological findings at presentation never achieved complete remission, although 3 had resolution of all transitional cell elements and 5 (10 per cent) were inevaluable. The toxicity of the regimen was generally acceptable but 6 per cent of the patients required hospitalization for neutropenic fever. While this active regimen can clinically (T) and pathologically (P) induce downstaging in a significant number of patients with primary bladder tumors, this pilot study has raised serious questions concerning the design of future nonrandomized and randomized neoadjuvant studies.

Adult↗
PubMed1988

Neoadjuvant M-VAC (methotrexate, vinblastine, doxorubicin and cisplatin) for extravesical urinary tract tumors.

A total of 11 patients with stage T2-4N0M0 extravesical tumors (prostate, prostatic urethra, urethra and ureter) received 1 to 4 cycles of neoadjuvant methotrexate, vinblastine, doxorubicin and cisplatin. Of 10 evaluable patients 4 (40 per cent) had downstaging to T0 disease with a clinical complete remission observed in 3 of 5 (60 per cent) with transitional cell tumors of the prostate and prostatic urethra. Four patients with urethral tumors of mixed or nontransitional histology failed to achieve a complete remission. The disease was staged pathologically in 4 patients: 1 had a partial remission and 3 had progression (all 4 had residual disease). Because therapy with methotrexate, vinblastine, doxorubicin and cisplatin induced only significant tumor regression of transitional cell elements of extravesical tumors and because it was ineffective against mixed histological tumors and in preventing new stage Tis lesions, surgical resection of such lesions is required.

Aged↗
PubMed1987

Lung tumors: percutaneous implantation of I-125 sources with CT treatment planning.

Seven patients with lung tumors underwent percutaneous implantation of iodine-125 sources into the tumor. Needle placement and seed implantation were effected with biplane fluoroscopy and a computer planning model based on computed tomography. No complications were encountered. Five of the seven patients underwent the procedure at the outpatient center and were discharged the same day. Follow-up radiologic evaluations were available for six patients; in all six the examination demonstrated tumor shrinkage, and in four tumor shrinkage was essentially complete.

Adenocarcinoma↗
PubMed1986

Intraluminal radiation therapy in the management of malignant biliary obstruction.

Fifteen patients with malignant biliary obstruction from carcinoma of the bile ducts, gallbladder, and pancreas (Group I) or metastatic disease (Group II) were treated with intraluminal radiation therapy (ILRT) at Memorial Sloan-Kettering Cancer Center. In 11 cases ILRT was used as a central boost in combination with 3000 cGy external beam radiation therapy (ERT). No significant treatment toxicity was observed. Cholangiographic response was observed in 2 of 12 evaluable patients. In no patient was long-term relief of jaundice without indwelling biliary stent achieved. Survival from treatment in eight Group I patients treated with ILRT +/- ERT was 3 to 13 months (median, 4.5). Survival in seven similarly treated Group II patients was 0.5 to 8 months (median, 4.0). Additional data for ten similar patients referred for ILRT but treated with ERT alone are presented. Analysis of this and other reports indicate the need for prospective controlled trials of the role of this regimen in the management of malignant biliary obstruction before wider application can be recommended.

Adolescent↗