Prediction of surgical difficulty in minimally invasive surgery for rectal cancer by use of MRI pelvimetry.

BACKGROUND: Technical difficulties in rectal surgery are often related to dissection in a limited surgical field. This study investigated the clinical value of MRI pelvimetry in the prediction of surgical difficulty associated with minimally invasive rectal surgery. METHODS: Patients with rectal cancer who underwent laparoscopic or robotic total mesorectal excision between 2005 and 2017 were reviewed retrospectively and categorized according to surgical difficulty on the basis of duration of surgery, conversion to an open procedure, use of the transanal approach, postoperative hospital stay, blood loss and postoperative complications. Preoperative clinical and MRI-related parameters were examined to develop a prediction model to estimate the extent of surgical difficulty, and to compare anastomotic leakage rates in the low- and high-grade surgical difficulty groups. Prognosis was investigated by calculating overall and relapse-free survival, and cumulative local and distant recurrence rates. RESULTS: Of 121 patients analysed, 104 (86·0 per cent) were categorized into the low-grade group and 17 (14·0 per cent) into the high-grade group. Multivariable analysis indicated that high-grade surgical difficulty was associated with a BMI above 25 kg/m2 (odds ratio (OR) 4·45, P = 0·033), tumour size 45 mm or more (OR 5·42, P = 0·042), anorectal angle 123° or more (OR 5·98, P = 0·028) and pelvic outlet less than 82·7 mm (OR 6·62, P = 0·048). All of these features were used to devise a four-variable scoring model to predict surgical difficulty. In patients categorized as high grade for surgical difficulty, the anastomotic leakage rate was 53 per cent (9 of 17 patients), compared with 9·6 per cent (10 of 104) in the low-grade group (P < 0·001). The high-grade group had a significantly higher local recurrence rate than the low-grade group (P = 0·002). CONCLUSION: This study highlights the impact of clinical variables and MRI pelvimetry in the prediction of surgical difficulty in minimally invasive rectal surgery.

ANTECEDENTES: Las dificultades técnicas en la cirugía del recto a menudo están relacionadas con la disección en un campo quirúrgico limitado. Este estudio se propuso investigar la utilidad clínica de la pelvimetría con MRI para predecir la dificultad quirúrgica asociada con la cirugía mínimamente invasiva del recto. MÉTODOS: Pacientes con cáncer de recto sometidos a resección total del mesorrecto laparoscópica o robótica entre 2005 y 2017 fueron revisados retrospectivamente y categorizados de acuerdo con la dificultad técnica en base al tiempo operatorio, conversión, uso de abordaje transanal, estancia hospitalaria postoperatoria, pérdida sanguínea y complicaciones postoperatorias. Se examinaron parámetros clínicos preoperatorios y relacionados con la MRI para desarrollar un modelo de predicción que estimara el grado de dificultad técnica y pudiera comparar la tasa de dehiscencias anastomóticas en los grupos de bajo y alto riesgo. También se evaluó el pronóstico con el cálculo de la supervivencia global, supervivencia libre de recidiva y tasas acumuladas de recidiva local y a distancia. RESULTADOS: De un total de 121 pacientes analizados, 104 pacientes (85,9%) fueron categorizados en el grupo con bajo grado de dificultad técnica, mientras que 17 pacientes (14,1%) lo fueron en el grupo de alto grado. En el análisis multivariable, un alto grado de dificultad técnica se asociaba con un índice de masa corporal (body mass index, BMI) > 25 kg/m2 (razón de oportunidades, odds ratio (OR), 4,5; P = 0,033), tamaño tumoral ≥ 45 mm (OR, 5,4; P = 0,042), ángulo anorrectal ≥ 123 grados (OR, 6,0; P = 0,028), estrecho pélvico < 82,7 mm (OR, 6,6; P = 0,048); en consecuencia, todas estas características fueron utilizadas para establecer un modelo de puntuación con 4 variables que pudiera predecir la dificultad técnica. En los pacientes categorizados como de alto grado de dificultad técnica, la tasa de dehiscencia anastomótica fue del 52,9%, mientras que en el grupo de bajo grado fue del 9,6% (P < 0,001). Finalmente, el grupo con alto grado mostró una tasa significativamente más elevada de recidiva local en comparación con el grupo de bajo grado (P = 0,002). CONCLUSIÓN: Este estudio pone de relieve el impacto de variables clínicas y de la pelvimetría con MRI para predecir la dificultad técnica en la cirugía mínimamente invasiva del recto.

Quantitative evaluation for the role of beta 146 His and beta 143 His residues in the Bohr effect of human hemoglobin in the presence of 0.1 M chloride ion.

Two different methods were used to determine the number of Bohr protons released upon oxygenation of human hemoglobin (Hb A) and Hb A lacking beta 146 His (des-His Hb A) at the pH ranging from pH 5.0 to 9.0 in the presence of 0.1 M Cl- at 25 degrees C. One is the direct differential titration method, the other is based on the measurement of oxygen affinity as a function of pH. The results obtained for Hb A or des-His Hb A with two methods were completely mutually consistent. The number of Bohr protons released from des-His Hb A upon oxygenation at pH 7.5 was about 44% less than that from Hb A, while at pH 5.5 the number of Bohr protons taken up by des-His Hb A was 20% greater than that by Hb A. The differences in the number of Bohr protons between Hb A and des-His Hb A could not be simply ascribed to the lack of beta 146 His from Hb A. The pK alpha values, which were determined by the deuterium exchange method using 1H NMR, were 8.0 for beta 146 His of deoxy-Hb A and 6.5 for that of CO Hb A, while those of beta 143 His were 5.2 for deoxy-Hb A and 6.0 for CO Hb A. From these pK alpha values, in addition to those of alpha 1 Val proposed for the modified CO and deoxy-Hb A with carbamylated beta chains by Van Beek and De Bruin (Van Beek, G. M., and De Bruin, S. H. (1980) Eur. J. Biochem. 105, 353-360), it became evident that almost all (about 92%) of the alkaline Bohr protons released upon oxygenation of Hb A in the presence of 0.1 M Cl- could be accounted for by the protons from these 2 residues, although the involvement of other histidine residues could not be denied. About half the acid Bohr protons from Hb A, which corresponds to the higher pH part (above pH 5.0) of the acid Bohr effect, could be explained by the involvement of beta 143 His residue. The residual acid Bohr effect in the more acidic pH region was presumably contributed by an amino acid residue with pK alpha values of 4.05 and 5.95 for the deoxy- and CO Hb A, respectively, although the amino acid residue was unspecified.(ABSTRACT TRUNCATED AT 400 WORDS)

Hydrolysis and epimerization kinetics of hetacillin in aqueous solution.

Methods were developed for quantitating epimerization to epihetacillin and hydrolysis to ampicillin in the alkaline degradation of hetacillin, and both rates in deuterium oxide at 35 degrees and in water at various temperatures were determined. In each case, plots of log k for the epimerization against pH or pD yielded straight lines with a positive slope, which verified the first-order dependence on the hydroxide ion or deuteroxide ion. The activation energy of the epimerization process was 21.2 kcal/mole. In aqueous solution at high pH, epimerization rather than conversion to ampicillin represents a major pathway of hetacillin degradation, although the beta-lactam ring of the hetacillin molecule is highly resistant to attack by the hydroxide ion.