Predicting Outcomes in Thyroidectomy and Parathyroidectomy: The Modified Five-Point Frailty Index Versus American Society of Anesthesiologists Classification

INTRODUCTION

Thyroidectomy and parathyroidectomy are relatively safe procedures, with overall morbidity rates of 2%-5%. The increasing age is associated with higher likelihood of poor outcomes. The modified five-point frailty index (mFI-5) is associated with complications, but many surgeons are unfamiliar with mFI-5. We assessed the accuracy of the mFI-5 versus the commonly-used American Society of Anesthesiologists (ASA) classification to predict complications following thyroidectomy and parathyroidectomy.

METHODS

Patients undergoing thyroidectomy or parathyroidectomy in 2015-2018 NSQIP datasets were identified. The mFI-5 scores were calculated by adding the number of the following comorbidities: congestive heart failure, hypertension requiring medication, chronic obstructive pulmonary disease, diabetes, and nonindependent functional status. Receiver operating characteristics curves were plotted for 30-d mortality and serious morbidity (defined as deep surgical site infection, dehiscence, unplanned intubation, failure to wean from the ventilator 48-h postoperatively, acute renal failure, pneumonia, pulmonary embolism, myocardial infarction, cardiac arrest requiring cardiopulmonary resuscitation, sepsis, septic shock, cerebrovascular accident, or reoperation) using mFI-5 and ASA classification. Areas under these curves (AUC) were compared.

RESULTS

Ninety-two thousand, six hundred and ninety-one patients were studied. The mFI-5 and ASA were fair predictors of 30-d mortality (AUC 0.75 and 0.82, respectively) and good predictors of serious morbidity (AUC 0.61 and 0.64). After stratification by age, ASA was superior to mFI-5 in predicting mortality for patients aged 65, 70, 80 y, and older, for the entire population and for thyroidectomy and parathyroidectomy separately.

CONCLUSIONS

The ASA classification is a better predictor of mortality and serious morbidity than mFI-5 among patients undergoing thyroidectomy or parathyroidectomy and may be a better prognostic indicator to use when counseling patients before low-risk neck surgery.

Surveillance Following Treatment of Esophageal Cancer

We describe the surveillance strategies after esophageal cancer treatment, whether local therapy, induction chemoradiation, or other definitive treatment such as trimodality therapy. We discuss the shortcomings of the different invasive and imaging studies, and the recommended stage-specific surveillance after local and organ-sparing approaches to esophageal cancer treatment.

The Economics of Patient Surgical Safety

Adverse surgical events are a major cause of morbidity, mortality, and disability worldwide. Serious reportable events, such as wrong site surgery, retained foreign bodies, and surgical fires, are preventable adverse events that have significant consequences. These "never events" are costly to the patient, health care systems, and society and have led to many efforts to reduce their occurrence. However, these costly events still occur, and more research is needed to obtain a better understanding of their causes and how to prevent them.

Outcomes in racial and ethnic minorities after revisional robotic-assisted metabolic and bariatric surgery: an analysis of the MBSAQIP database

BACKGROUND

Robotic-assisted metabolic and bariatric surgery (MBS) is being performed with increased frequency in the United States, including for revisional MBS. However, little is known about perioperative outcomes between racial and ethnic cohorts after revisional robotic-assisted MBS.

OBJECTIVE

The goal of our study was to determine if there are racial differences in outcomes after robotic-assisted revisional MBS.

SETTING

University Hospital, United States.

METHODS

Using the 2015-2017 Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program database, we identified patients undergoing revisional MBS by a robotic-assisted approach. Univariate analyses were performed of unmatched and matched racial and ethnic cohorts, comparing black versus white patients and Hispanic versus white patients.

RESULTS

Of 2027 robotic-assisted revisional MBS cases in the database, 1922 were included in our analysis, including 67%, 22.6%, and 10.4% white, black, and Hispanic patients, respectively. At baseline, there were some differences in patient characteristics between racial and ethnic cohorts. After propensity matching, outcomes between black and white patients were similar, except for higher rates of superficial surgical site infection among white patients (P = .05) and higher rates of organ space surgical site infection in black patients (P = .05). Outcomes were also similar between matched white and Hispanic patients, except for a higher bleeding in white patients (2% versus 0%, P = .04). There were no mortality or morbidity differences between racial and ethnic cohorts.

CONCLUSION

Morbidity and mortality after robotic-assisted revisional MBS do not seem to be mediated by race or ethnicity.

Outcomes in conventional laparoscopic versus robotic-assisted primary bariatric surgery: a retrospective, case-controlled study of the MBSAQIP database

Introduction

Robotic-assisted bariatric surgery is increasingly performed. There remains controversy about the overall benefit of robotic-assisted (RBS) compared to conventional laparoscopic (LBS) bariatric surgery. In this study, we used a large national risk-stratified bariatric clinical database to compare outcomes between robotic and laparoscopic gastric bypass (RNYGB) and sleeve gastrectomy (SG).

Methods

A retrospective analysis of the 2015 and 2016 Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) Participant Use Data File (PUF) was performed. Primary robotic and laparoscopic RYNGB and SG were analyzed. Descriptive analysis was performed of the unmatched cohorts, followed by 1:3 case-controlled matching. Cases and controls were matched by patient demographics and pre-operative comorbidities, and peri-operative outcomes compared.

Results

77,991 Roux-en-Y gastric bypass (RnYGB) (7.5% robotic-assisted) and 189,503 SG (6.8% robotic-assisted) cases were identified. Operative length was significantly higher in both the robotic-assisted RnYGB and SG cohorts (p < 0.0001). Outcomes were similar between the robotic-assisted and laparoscopic RnYGB cohorts, except a lower mortality rate (p = 0.05), transfusion requirement (p = 0.005), aggregate bleeding (p = 0.04), and surgical site infections (SSI) (p = 0.006) in the robotic-assisted cohort. Outcomes were also similar between robotic-assisted and laparoscopic SG, except for a longer length of stay (p < 0.0001) and higher rates of conversion (p < 0.0001), 30-day intervention (p = 0.01), operative drain present (p < 0.0001), sepsis (p = 0.01), and organ space SSI (p = 0.0002) in the robotic cohort. Bleeding was lower in the robotic SG cohort and mortality was similar.

Conclusion

Both robotic-assisted and laparoscopic RnYGB and SG are overall very safe. Robotic-assisted gastric bypass is associated with a lower mortality and morbidity; however, a clear benefit for robotic-assisted SG compared to laparoscopic SG was not seen. Given the longer operative and hospital duration, robotic SG is not cost-effective.

Electronic supplementary material

The online version of this article (10.1007/s00464-019-06915-7) contains supplementary material, which is available to authorized users.

Outcomes in conventional laparoscopic versus robotic-assisted revisional bariatric surgery: a retrospective, case-controlled study of the MBSAQIP database

Introduction

Revisional bariatric surgery is being increasingly performed and is associated with higher operative risks. Optimal techniques to minimize complications remain controversial. Here, we report a retrospective review of the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) Participant User Files (PUF) database, comparing outcomes between revision RBS and LBS.

Methods

The 2015 and 2016 MBSAQIP PUF database was retrospectively reviewed. Revision cases were identified using the Revision/Conversion Flag. Selected cases were further stratified by surgical approach. Subgroup analysis of sleeve gastrectomy and gastric bypass cases was performed. Case–controlled matching (1:1) was performed of the RBS and LBS cohorts, including gastric bypass and sleeve gastrectomy cohorts separately. Cases and controls were match by demographics, ASA classification, and preoperative comorbidities.

Results

26,404 revision cases were identified (93.3% LBS, 6.7% RBS). 85.6% were female and 67% white. Mean age and BMI were 48 years and 40.9 kg/m². 1144 matched RBS and LBS cases were identified. RBS was associated with longer operative duration (p < 0.0001), LOS (p = 0.0002) and a higher rate of ICU admissions (1.3% vs 0.5%, p = 0.05). Aggregate bleeding and leak rates were higher in the RBS cohort. In both gastric bypass and sleeve gastrectomy cohorts, the robotic-assisted surgery remain associated with longer operative duration (p < 0.0001). In gastric bypass, rates of aggregate leak and bleeding were higher with robotic surgery, while transfusion was higher with laparoscopy. For sleeve gastrectomy cases, reoperation, readmission, intervention, sepsis, organ space SSI, and transfusion were higher with robotic surgery.

Conclusion

In this matched cohort analysis of revision bariatric surgery, both approaches were overall safe. RBS was associated with longer operative duration and higher rates of some complications. Complications were higher in the robotic sleeve cohort. Robotic is likely less cost-effective with no clear patient safety benefit, particularly for sleeve gastrectomy cases.

Is non-invasive indocyanine-green angiography a useful adjunct for the debridement of infected sternal wounds?

Laser-assisted indocyanine-green imaging (ICG) has a wide range of surgical applications, and has been used in reconstructive surgery to aid in assessing the viability of free tissue transfers and to help predict poor tissue perfusion. However, its indications for use is limited to assessing free flap tissue perfusion, coronary artery perfusion during coronary artery bypass (CABG), and tissue perfusion in diabetic foot ulcers, to name a few. This system has been proven to be a safe, reliable adjunctive modality to assess microvascular compromise or poor perfusion peri-operatively, which could minimize skin necrosis and other post-operative complications (Further et al., 2013).¹ The ability to objectively assess tissue perfusion has led to improved post-operative outcomes in breast, abdominal wall, colorectal, and cardiac surgery. To date, no studies have reviewed the use of ICG in delineating devitalized bone during sternal wound debridement after cardiac surgery. At our institution, we have encountered a cohort of patients with post-cardiac surgery sternal wound infections who have required debridement of infected and devitalized bone. We propose that SPY technology aids in delineating this devitalized bone, and may aid in the timing muscle flap coverage. In this paper, we will demonstrate two cases of patients who had post-operative sternal wound infections after undergoing cardiac surgery for which ICG was used to demarcate debridement zones and subsequent flap coverage. In these cases, ICG allowed for efficient and reliable intraoperative evaluation of bony perfusion and has aided in early adequate debridement and flap coverage.

CHACO outreach project: the development of a primary health care-based medical genetic service in an Argentinean province

Dissemination of knowledge in genetics to be applied in medicine has created a growing need for capacity building in health care workers. The CAPABILITY ARGENTINA outreach project protocol was designed as a model to introduce genetics in areas without genetic services. Our aim was for genetic health care to become part of primary care in an Argentine province lacking genetic services. The program was innovative as professionals from the referral center (Garrahan Hospital S.A.M.I.C.) traveled to remote areas to train professionals through problem-based education. A logical framework was designed for a local needs assessment. Teaching materials (Powerpoint presentations, printed syllabus, and CD) and a web page were developed. A demonstration project was carried out in the Province of Chaco, Argentina. A total of 485 health workers were trained. The number of consultations increased significantly in participating areas comparing before and after the training period. To support this increase, a complementary project was set up from a public hospital sponsored from within Argentina to build a cytogenetic laboratory in the capital of the Province of Chaco. The model was improved for reproduction in other areas in Argentina. CAPABILITY ARGENTINA is a capacity building model for training of primary care professionals in genetics that may be applied to other medical specialties. The outcomes of the programme have a direct impact on clinical practice.

Maize leaf elongation: continuous measurements and close dependence on plant water status

A simple method was developed for measuring extensive intact leaves of monocots on a minute-by-minute basis. Growth was markedly reduced by a slight reduction in leaf water potential. When plants mildly deficient in water were irrigated, growth resumed virtually instantly. The transitional rapid growth aftr watering suggests that water deficit increased cell extensibility.

[Vibrio cholerae sepsis in the neonate]

Vibrio cholerae sepsis is infrequent, especially in neonates although sporadic cases have been reported in older patients. We report the case of a neonate who was admitted to the intensive care unit for hypovolemic shock secondary to diarrhea caused by V. cholerae that developed into bacteremia. The predisposing factors were low socioeconomic status, home delivery, delayed presentation at the health center, and active maternal gastrointestinal infection with V. cholerae. The organism identified in blood and feces culture was identified as V. cholerae 0 -1, biotype Thor, serotype Ogawa, which correlated with the clinical presentation.

Tumour necrosis factor microsatellites and HLA-DRB1*, HLA-DQA1*, and HLA-DQB1* alleles in Peruvian patients with rheumatoid arthritis

OBJECTIVE

To study the association between rheumatoid arthritis (RA) and HLA and tumour necrosis factor (TNF) polymorphism in Peruvian mestizo patients in comparison with ethnically similar controls.

METHODS

Seventy nine patients with RA and 65 ethnically matched healthy controls were genotyped for HLA-DRB1, HLA-DQA1, HLA-DQB1, and TNFalpha and TNFbeta alleles using PCR amplification. Clinical severity was assessed as mild, moderate, or severe in 35 of the patients.

RESULTS

TNFalpha6 showed the strongest association with disease susceptibility. The TNFalpha6 allele was more common in patients than in controls (p<0.0076) and the proportion of patients with at least one copy of this allele was greater (p<0.015, relative risk 2.35). Among the HLA-DRB1* alleles with the shared epitope sequence, only the DRB1*1402 allele was significantly increased in patients compared with controls (p<0.0311), as was the proportion of patients with at least one copy of this allele (p<0.0232, relative risk 2.74). In contrast, the overall frequency of alleles with the shared epitope was not different in patients and controls. The haplotype HLA-DRB1*1402-DQB1*0301-DQA1*0401 was significantly more common in patients. TNFalpha6 was more common in patients whether or not they had this haplotype. None of the 11 patients lacking the TNFalpha6 allele had severe disease.

CONCLUSIONS

This study shows for the first time that TNF gene polymorphism is associated with susceptibility to RA in a non-white population. TNFalpha6 and HLA-DRB1*1402 independently conferred significantly increased risk in Peruvian mestizo patients.

Tolerability profiles of rofecoxib (Vioxx) and Arthrotec. A comparison of six weeks treatment in patients with osteoarthritis

OBJECTIVE

To compare the incidence of selected spontaneously reported adverse events (AEs) in patients with osteoarthritis (OA) treated with rofecoxib (VIOXX, 12.5 mg qd) or Arthrotec (diclofenac 50 mg/misoprostol 200 mcg bid).

METHODS

Double-blind, parallel-group, 6-week study of patients aged > or = 40 years with a clinical diagnosis of OA treated with rofecoxib or Arthrotec. Primary endpoint: self-reported diarrhea; secondary endpoints: abdominal pain, discontinuations due to AEs, GI AEs and NSAID-type GI AEs (ie., acid reflux, dyspepsia, epigastric discomfort, heartburn, nausea, vomiting).

RESULTS

Among 483 patients (80.3% females, mean age 62.1), the rofecoxib group vs the Arthrotec group respectively reported diarrhea 6.2% vs 16.2% (p<0.001); drug-related diarrhea 3.7% vs 16.2% (p<0.001); one or more clinical AEs 52.9% vs 73.0% (p<0.001); GI AEs 28.9% vs 48.5% (p<0.001); NSAID-type GI AEs 18.6% vs 29.9% (p=0.004); discontinuations due to abdominal pain 0.4% vs 3.7% (p<0.05); and discontinuations due to any AE 4.1% vs 9.1% (p=0.029). No significant differences were observed in efficacy.

CONCLUSION

Rofecoxib 12.5 mg qd has improved GI tolerability and similar efficacy compared to Arthrotec (diclofenac 50 mg/misoprostol 200 mcg bid).

Comparison of the effect of rofecoxib (a cyclooxygenase 2 inhibitor), ibuprofen, and placebo on the gastroduodenal mucosa of patients with osteoarthritis: a randomized, double-blind, placebo-controlled trial. The Rofecoxib Osteoarthritis Endoscopy Multinational Study Group

OBJECTIVE

This randomized, double-blind study tested the hypothesis that rofecoxib, a drug that specifically inhibits cyclooxygenase 2, would cause fewer gastroduodenal ulcers than ibuprofen (in a multicenter trial), and its side effects would be equivalent to those of placebo (in a prespecified analysis combining the results with another trial of identical design).

METHODS

Seven hundred seventy-five patients with osteoarthritis were randomized to receive rofecoxib at a dosage of 25 mg or 50 mg once daily, ibuprofen 800 mg 3 times daily, or placebo. Gastroduodenal ulceration was assessed by endoscopy at 6, 12, and (for active treatment) 24 weeks. The primary and secondary end points were the incidence of gastroduodenal ulcers at 12 and 24 weeks, respectively.

RESULTS

Ulcers were significantly less common (P < 0.001) following treatment with rofecoxib (25 mg or 50 mg) than with ibuprofen after 12 weeks (5.3% and 8.8% versus 29.2%, respectively) or 24 weeks (9.9% and 12.4% versus 46.8%, respectively). In the combined analysis, the 12-week ulcer incidence with 25 mg rofecoxib (4.7%) and with placebo (7.3%) satisfied prespecified criteria for equivalence.

CONCLUSION

At 2-4 times the therapeutically effective dose, rofecoxib caused fewer endoscopically detected ulcers than did ibuprofen. Rofecoxib at a dose of 25 mg (the highest dose recommended for osteoarthritis) satisfied prespecified criteria for equivalence to placebo.

Comparison of the effect of rofecoxib (a cyclooxygenase 2 inhibitor), ibuprofen, and placebo on the gastroduodenal mucosa of patients with osteoarthritis: a randomized, double-blind, placebo-controlled trial. The Rofecoxib Osteoarthritis Endoscopy Multinational Study Group

OBJECTIVE

This randomized, double-blind study tested the hypothesis that rofecoxib, a drug that specifically inhibits cyclooxygenase 2, would cause fewer gastroduodenal ulcers than ibuprofen (in a multicenter trial), and its side effects would be equivalent to those of placebo (in a prespecified analysis combining the results with another trial of identical design).

METHODS

Seven hundred seventy-five patients with osteoarthritis were randomized to receive rofecoxib at a dosage of 25 mg or 50 mg once daily, ibuprofen 800 mg 3 times daily, or placebo. Gastroduodenal ulceration was assessed by endoscopy at 6, 12, and (for active treatment) 24 weeks. The primary and secondary end points were the incidence of gastroduodenal ulcers at 12 and 24 weeks, respectively.

RESULTS

Ulcers were significantly less common (P < 0.001) following treatment with rofecoxib (25 mg or 50 mg) than with ibuprofen after 12 weeks (5.3% and 8.8% versus 29.2%, respectively) or 24 weeks (9.9% and 12.4% versus 46.8%, respectively). In the combined analysis, the 12-week ulcer incidence with 25 mg rofecoxib (4.7%) and with placebo (7.3%) satisfied prespecified criteria for equivalence.

CONCLUSION

At 2-4 times the therapeutically effective dose, rofecoxib caused fewer endoscopically detected ulcers than did ibuprofen. Rofecoxib at a dose of 25 mg (the highest dose recommended for osteoarthritis) satisfied prespecified criteria for equivalence to placebo.

[Standardization of ELISA IgM and IgA for immunodiagnosis of human trichinosis]

An ELISA test for trichinosis using as antigen a larvae soluble fraction from Trichinella spiralis was carried out for the detection of IgM and IgA specific antibodies in 45 serum samples from patients confirmed or suspected to have trichinosis by strong clinical and epidemiological evidences. All the patients had positive serology detected by precipitin test, bentonite floculation test, indirect hemagglutination test and ELISA IgG test. The cut-off value was determined using two criteria. Criterion A was determined in each plate, using three positive controls and two negative ones; the average of the negative controls and the weakest positive control, multiplied by a 1.2 factor was, considered the cut-off value. Criterion B was determined using the average plus three standard deviations from 64 apparently healthy persons serum samples. In both cases, three serum dilutions (1:10, 1:100 and 1:500) were used. The sensitivity of ELISA IgM was 100.0, 93.3 and 82.2% using serum dilutions of 1:10, 1:100 and 1:500 respectively (criterion A) and 100.0, 97.8 and 95.6% for the same dilutions (criterion B), whereas the values for ELISA IgA were: 100.0, 91.1 and 86.7% (criterion A) and 100.0, 100.0 and 91.1% (criterion B). In order to find out the specificity of ELISA IgM and ELISA IgA, additional 118 serum samples from individuals with other parasitoses, such as cysticercosis (18) hydatidosis (39), fascioliasis (12), toxocariasis (30), Chagas' disease (12) and individuals with non-specific eosinophilia (7), were also tested. ELISA IgM presented a specificity of 92.3, 93.4 and 97.3% (criterion A) and 96.2, 97.8 and 97.8% (criterion B) whereas the results for ELISA IgA were 97.8, 98.9 and 99.4% (criterion A) and 98.4% for the 1:10 and 1:100 dilutions and 100.0% for the 1:500 dilution (criterion B). The positive predictive values of ELISA IgM were 76.3, 77.8 and 88.1% (criterion A) and 86.5, 91.7 and 91.5% (criterion B) whereas the negative ones were 100.0, 98.3 and 95.7% (criterion A) and 100.0, 99.4 and 98.9% (criterion B). The positive predictive values of ELISA IgA were 91.8, 95.3 and 97.5% (criterion A) and 93.8, 93.8 and 100.0% (criterion B) whereas the negatives ones were: 100.0, 97.8 and 96.8% (criterion A) and 100.0, 100.0 and 97.8% (criterion B). The use of ELISA IgM and ELISA IgA in the immunodiagnosis of trichinosis is discussed.

Effects of antihypertensive treatment on cardiac IGF-1 during prevention of ventricular hypertrophy in the rat

There is some evidence that cardiac rather than circulating insulin-like growth factor-1 (IGF-1) levels contribute to the development of renovascular hypertensive left ventricular hypertrophy (LVH), remaining unknown the effects of antihypertensive drugs on IGF-1 levels. We have assessed here the preventive effects of enalapril, losartan, propanolol and alpha-methyldopa on left ventricle (LV) and circulating IGF-1 levels in a rat model of hypertension and LVH (Goldblatt, GB). Our results show that relative LV mass and the LV content of IGF-1 were significantly lower with all antihypertensive drugs in GB rats (p<0.001). Serum concentrations of IGF-1 were lower in GB rats treated with enalapril, alpha-methyldopa and propanolol (p<0.01), but not in those treated with losartan. These results support the hypothesis that local rather than seric IGF-1 contributes to the development of left ventricular hypertrophy induced by pressure overload in the rat.

Selective increase in cardiac IGF-1 in a rat model of ventricular hypertrophy

There is evidence that insulin-like growth factor-1 (IGF-1) plays a role in the development of left ventricular hypertrophy, but it is uncertain whether cardiac IGF-1 changes before or after hypertension is established, and whether circulating IGF-1 are involved in cardiac hypertrophy. We have investigated changes in circulating and left ventricular IGF-1 and in the expression of the IGF-1 gene in the left ventricles of rats during the development of hypertensive left ventricular hypertrophy (Goldblatt model; 2 kidney-1 clamped). Our results show that the left ventricular contents of IGF-1 and its mRNA were increased at one and four weeks of hypertension and hypertrophy, and that both returned to control values after nine weeks. These changes were unrelated to the seric concentration of IGF-1 in the blood. These results show that local rather than circulating IGF-1 levels contributed to the development of renovascular hypertensive left ventricular hypertrophy.

Changes in dietary fiber content and its composition as affected by processing of black beans (Phaseolus vulgaris, Tamazulapa variety)

This paper presents the effect that the traditional cooking process of black beans (Phaseolus vulgaris, Tamazulapa variety) has on the quantity and composition of soluble (SDF) and insoluble (IDF) dietary fiber of beans, as well as on its protein digestibility and protein quality. There was an increase of IDF from 18.1% in cooked beans to 22.4% in fried beans, and a decrease in SDF from 8.4% to 6.6%, respectively. Starch content decreased from 34.5% to 31.3%. No change was found in lignin. The xylose content was higher in IDF than in SDF and decreased to some extent from cooked to fried beans. Arabinose content was similar in IDF and SDF with no change caused by processing. The fraction containing glucose, mannose and galactose in IDF was higher than in SDF, the content increasing in IDF and decreasing in SDF, with processing. Protein content in IDF was higher than in SDF, with no major change when processing. About 29.5% of the total protein of beans was bound in DF. Protein digestibility and protein quality decreased from cooked to fried beans and was positively related to IDF.

[Effect of reheating on iron availability and the protein nutritive value of cooked black bean (Phaseolus vulgaris)]

In Guatemala, at the rural level, beans are prepared for family consumption every two days. Beans are cooked again every 12 hours for 15 minutes prior to their consumption. Due to the adverse effect that the process causes on nutritive value, the present study evaluated the method and preparation practice of beans on protein value; tannin and soluble and ionizable iron content. As to the effect of re-cooking on protein level, findings revealed that there were no significant statistical effects on net protein ratio (NPR) or in protein efficiency ratio (PER) and number of bean cooking. Nevertheless, a constant effect in quality in the first and second cooking procedure was detected. The second cooking gave a similar value as the first. Also, the first and second heating reduced protein digestibility, but the third gave a value similar to the initial one. No changes were observed in the digestibility of dry matter. Relatively high amounts of protein were found in the cooking broth, which was not affected by the number of heating. It was also found that the bean broth contained high levels of tannins in the initial heating, decreasing later significantly. The same was observed in the cooked beans alone and in beans with their broth. With respect to iron, findings showed a relatively high transference of beans to broth, in total iron as well as in soluble, ionizable and insoluble iron. No changes were observed in whole beans without broth caused by number of heatings, on total, soluble or ionizable iron. In beans with their broth, a similar effect was observed, although a slight increase in insoluble iron was detected at the end of heating. A decrease in soluble and insoluble iron was observed in broth with number of heatings. Correlations were calculated among the parameters studied, which suggested an effect of tannins on the bioavailability of iron caused by tannins.

[Dietary fiber content and nitrogen digestibility in Central American foods: Guatemala]

The study herein reported presents information on the dietary fiber content of four food groups consumed in Central America. These are: cereals, grains and products; raw and processed beans; raw and processed vegetables, and starchy foods such as potatoes, cassava and plantain. Besides data on soluble and insoluble fiber, data on in vitro protein digestibility are included. The total dietary fiber content of the wheat flour products varied from 1.62 to 2.83% on a fresh basis, with the exception of whole-wheat bread, which showed a 7.57% content. The maize tortilla presented values ranging from 3.96 to 5.21% in respect to beans, and the values for cooked and raw beans fluctuated between 6.36 and 7.00%, independent of the color; however, fried beans reported values from 15.28 to 17.58%. Vegetables contained total dietary fiber values of 1.51 to 4.34, and the tubers, from 1.31 to 2.86%.

[Intake of dietary fiber in the Central American isthmus: nutritional implications]

Mean intakes of dietary fiber (DF) were estimated in the population of Central America and Panama, using the results of dietary surveys conducted in 1969 and 1986 both in rural and urban areas, as well as data on the DF content of foods as consumed in the region. Data on preschool children were also estimated. The results indicated that DF intake in urban areas is lower than that of rural areas, particularly in Costa Rica and Panama. In 1969, intake varied from 32g in El Salvador to 15g in Panama in urban areas, while in rural areas intake was from 45g in El Salvador to 13g in Panama. The foods which contributed most to the total intake in Guatemala, El Salvador and Honduras were tortillas and beans, while in Costa Rica and Panama, beans provided the largest intake. In preeschool children, intake was 12.5g in El Salvador and 5.4g in Costa Rica in 1969, which is the same tendency as that found for adults. From more recent data on food intake, it was found that DF intake had decreased in the rural areas of El Salvador, Honduras and Costa Rica, being between 4 and 9% in the first two countries and 12% in Costa Rica. In the urban area of the latter, from 1969 to 1986 a decrease in DF intake of around 20% has taken place.

Water Relations, Diurnal Acidity Changes, and Productivity of a Cultivated Cactus, Opuntia ficus-indica

Physiological responses of the Crassulacean acid metabolism (CAM) plant Opuntia ficus-indica (Cactaceae) were studied on a commercial plantation in central Chile. Young cladodes (flattened stems) and flower buds exhibited daytime stomatal opening, whereas mature cladodes and fruit exhibited the nocturnal stomatal opening characteristic of CAM plants. Severe water stress suppressed the nocturnal stomatal opening by mature cladodes, but their high water vapor conductance occurring near dawn was not affected. Nocturnal acidity increases were not as sensitive to water stress as was the nocturnal stomatal opening. The magnitude of the nocturnal acidity increases depended on the total daily photosynthetically active radiation (PAR), being 90% PAR-saturated at 27 moles per square meter per day for a mean nighttime air temperature of 5 degrees C and at 20 moles per square meter per day for 18 degrees C. Inasmuch as the PAR received on unshaded vertical surfaces averaged about 21 moles per square meter per day, nocturnal acidity increases by the cladodes were on the verge of being PAR-limited in the field. The net assimilation rate, which was positive throughout the year, annually averaged 3.4 grams per square meter per day for 1.0- and 2.0-year-old plants. Plants that were 5.4 years old had 7.2 square meters of cladode surface area (both sides) and an annual dry weight productivity of 13 megagrams (metric tons) per hectare per year when their ground cover was 32%. This substantial productivity for a CAM plant was accompanied by the highest nocturnal acidity increase so far observed in the field, 0.78 mole H(+) per square meter.

Model for the interaction of membrane-bound substrates and enzymes. Hydrolysis of ganglioside GD1a by sialidase of neuronal membranes isolated from calf brain

Microsomes and synaptosomes isolated from calf brain contain a sialidase which cleaves ganglioside substrates. The hydrolysis of [3H]ganglioside GD1a by the membrane-bound enzyme has been studied under various conditions. The reaction rate decreased with increasing ionic strength in the incubation mixture, and was progressively enhanced by increasing concentrations of the primary alcohols n-pentanol to n-octanol. This stimulation correlates quantitatively with an increase in membrane 'fluidity' caused by these alcohols as measured by fluorescence depolarization employing 1,6-diphenyl-1,3,5-hexatriene as probe. The dependence of the reaction rate on the amount of enzyme in the incubation mixture was linear only with water-soluble substrates but not with the lipophilic ganglioside substrate. Evidence is presented that lipophilic substrate and enzyme interact mainly within the plane of the membrane presumably by lateral diffusion. Taking this into consideration Michaelis-Menten theory was modified accordingly. As predicted, apparent Km values increased linearly with the amount of membrane-bound enzyme added and decreased with the concentration of n-hexanol in the incubation mixture. In the presence of varying n-hexanol concentrations the apparent Km-value decreased with increasing membrane 'fluidity', as measured by fluorescence depolarization of 1,6-diphenyl-1,3,5-hexatriene. On the other hand, as expected, V values were not affected by membrane 'fluidity' and increased linearly with the amount of membrane protein.

Diurnal growth trends, water potential, and osmotic adjustment of maize and sorghum leaves in the field

The daily cycle of leaf elongation rate, water potential, and solute potential of maize and sorghum, as well as temperature, were monitored in the field. Major climatic features were high radiation and a minimum air temperature of about 12 C. Leaf elongation of both crops was slowest at night, presumably because of low temperature. Peak elongation rates were in daytime when leaf water potential (Psi) was low. Solute potential also decreased during daylight, thus permitting the maintenance of appreciable turgor pressure, a critical parameter for cell expansion.Leaf Psi versus relative water content (RWC) curves were developed by sampling detached leaves at intervals as they dried quickly in the laboratory. At a given RWC, Psi was lower in leaves at midday than early in the morning, which is evidence that the decrease in psi. at midday was caused by an increase in the amount of solute in the tissue. Estimates of psi. at 100% RWC were 4 bars lower at midday than early in the morning in both crops. Soluble sugars, mainly nonreducing, accounted for most of the observed psi. decrease in sorghum leaves. Shading the leaves from light eliminated most of the solute buildup.

Immediate and subsequent growth responses of maize leaves to changes in water status

Elongation of intact young leaves of maize was found to be dynamically dependent on soil water supply. With adequate water, elongation was remarkably constant but slowed when the water potential of the soil in pots dropped from -0.1 to -0.2 bar and stopped when it dropped to -2.5 bars. The corresponding range of leaf water potential was -2.8 to -7 bars. Elongation resumed in less than a few seconds after a mildly water-stressed plant was rewatered.The effects on leaf elongation of step-wise changes in water potential of the root solution were determined. When the water potential of the root medium suddenly decreased below 0 bar, growth stopped initially and then resumed at a lower rate. When the water potential was suddenly increased back to 0 bar, growth accelerated transitorily to a high rate before slowing to the steady state rate. These results suggest an increase in cell extensibility during water stress.Leaves stressed for 1 or more days attained after rewatering almost the length of the control leaves. Growth rate after rewatering did not exceed that of the control at the corresponding developmental stage except during the short transitory rapid phase lasting only a fraction of an hour.As stress developed, growth stopped before carbon dioxide assimilation decreased noticeably. Upon the release of mild and short stress, the transitory rapid growth completely made up for the reduced elongation during stress, suggesting that metabolic processes for cell expansion might have proceeded unchecked during the stress period.The sensitivity and rapidity of response to changes in water status all point to the direct role of water in growth; its uptake provides the physical force for cell enlargement.