Controlled release of insulin through hydrogels of (acrylic acid)/trimethylolpropane triacrylate

Hydrogels of poly(acrylic acid) crosslinked with trimethylolpropane triacrylate (TMPTA) were produced through solution polymerization. After these hydrogels were loaded with insulin solution, they evidenced swelling. Experiments of controlled release of insulin through the hydrogels were performed in acidic and basic media in order to evaluate the rates of release of this protein provided by the referred copolymer. Additionally, a mathematical description of the system based on differential mass balance was made and simulated in MATLAB. The model consists of a system of differential equations which was solved numerically. As expected, the values of swelling index at the equilibrium and the rates of insulin release were inversely proportional to the degree of crosslinking. The mathematical model provided reliable predictions of release profiles with fitted values of diffusivity of insulin through the hydrogels in the range of 6.0 x 10(-7)-1.3 x 10(-6) cm(2)/s. The fitted and experimental values of partition coefficients of insulin between the hydrogel and the medium were lower for basic media, pointing out good affinity of insulin for these media in comparison to the acidic solutions

Polymerization kinetics of pre-heated composite.

Temperature affects the polymerization behavior of dimethacrylate-based materials. This study describes the influence of pre-polymerization temperature and exposure duration on polymerization kinetics of a commercial dental photo-activated composite at the top and at 2-mm depth. We used the temperature-controlled stage of a diamond-attenuated-total-reflectance unit to pre-set composite temperature between 3 degrees and 60 degrees C. Composite was light-exposed by a conventional quartz-tungsten-halogen curing unit for 5, 10, 20, or 40 sec. Real-time conversion, maximum conversion rate (R(p)(max)), time to achieve R(p)(max), and conversion at R(p)(max) were calculated from infrared spectra. Composite pre-warming enhanced maximal polymerization rate and overall monomer conversion (top significantly greater than 2 mm). Time when R(p)(max) occurred did not change with temperature, but occurred sooner at the top than at 2-mm depth. Conversion at R(p)(max) increased with temperature, allowing more of the reaction to occur prior to vitrification than at room temperature.

[Effect of total++ time of extracorporeal circulation in in myocardial revascularization surgery on urinary urea nitrogen loss]. / Efeito do tempo total de circulação extracorpórea em cirurgia de revascularização miocárdica sobre a perda urinária de nitrogênio na forma de uréia.

Cardiopulmonary bypass probably should be an important factor increasing surgical stress when heart surgery is focused. This study was undertaken in order to evaluate the role of cardiopulmonary bypass in proteic catabolism. Study group consisted of patients who underwent cardiac aortic bypass graft as an isolated procedure. Inclusion criteria were elective surgery and absence of comorbidities after a rigorous preoperatory evaluation. One hundred and five patients were studied prospectively and urinary nitrogen loss was measured in the first 24 hour postoperative period. Operations performed were standard cardiopulmonary bypass procedures, under cardiopulmonary bypass, moderate hypothermia and hemodilution. Saphenous veins and mammary artery grafts were performed in all cases. Correlation and multiple linear regression were used. There was found no correlation between urinary nitrogen loss and age, gender and time under cardiopulmonary bypass. A positive correlation was found between number of grafts and increased urinary nitrogen loss. Further studies comparing cardiac aortic bypass graft with and without cardiopulmonary bypass are suggested.

Economic longitudinal lateral posterior thoracothomy. Minimally invasive option in pulmonary resections.

BACKGROUND: Pulmonary resections are usually performed through posterolateral thoracotomy. However this approach has been associated largely with early and late incidence of postoperative morbidity. Several lateral chest approaches have been reported in the medical literature with the objective to decrease morbidity due to thoracotomy. The aim of this study was to evaluate the results of pulmonary resection, performed by means of a minor thoracotomy in the posterior axillary region. METHODS: The skin incision was longitudinal and scapular; shoulder and chest wall muscles were not cut, a subperiosteally lateral portion of rib was removed and the thoracic wall was opened in the rib bed. The approach in this place allowed a smaller skin incision, skin flaps were not necessary and the chest wall opening stayed in a better position in relation to the pulmonary hilum, facilitating the exposition of its anterior and posterior faces. From January 1994 to December 1996 seventy-eight consecutively non-selected patients underwent eighty surgical procedures for several kinds of pulmonary resections. RESULTS: All surgical procedures occurred without difficulties and with a lower number of postoperative complications. A very good aesthetic result was reached. CONCLUSIONS: We believe this chest approach may be a good choice for pulmonary resection.

[Polyalveolosis: pathogenesis of congenital lobar emphysema?]. / Polialveolose: patogênese do enfisema lobar congênito?

BACKGROUND: Congenital lobar emphysema is an unusual condition and its pathogenesis remains unknown. The variety of findings in pathology studies of the resected specimens led to increasing academic interest. About 50 per cent of the cases have no definitive diagnosis in pathology. The most recent theory proposes an increased number of alveoli within each acinus (polyalveolar lobe). PURPOSE: The aim of this paper is to report the morphometric measures of surgical specimens of 12 patients with congenital lobar emphysema, using the Emery and Mithal technique (radial alveolar count). METHODS: We made a case-control study, classifying the cases by age. Mann-Whitney's U test and linear regression techniques were used in data analysis: Mann-Whitney's U in comparing the cases and respective controls and linear regression to evaluate the influence of age in the measures found. RESULTS: The results revealed a significantly higher radial alveolar count than expected for the age group under 3 years; no difference was observed in the age group between 3 and 7 years and in children older than 7, the radial alveolar count was lower than expected. The normal development of the lung consists in an increasing number of alveoli increase from birth until adulthood, but this number remains constant, independent of age in congenital lobar emphysema. CONCLUSIONS: Such findings allow us to conclude that polyalveolar lobe can and must be diagnosed by a simple and practical method, such as the radial alveolar count, which decreases the incidence of the unknown etiology. The findings of an increased number of alveoli on patients younger than 3 is related to congenital lobar emphysema, since the number of alveoli does not increase in congenital lobar emphysema, just the opposite to what one would expect in the normal development of the lung.

Polialveolose: patogênese do enfisema lobar congênito? / Polyalveolosis: pathogenesis of congenital lobar emphysema?

Introduçao. O enfisema lobar congênito é doença rara, cuja patogênese permanece desconhecida. O interesse acadêmico reside na falta de uniformidade dos achados anatomopatológicos. Em cerca de 50 por cento, nao se consegue definir a lesao anatomopatológica. A teoria mais recente relaciona esta doença com um número aumentado de alvéolos dentro de cada ácino pulmonar. Objetivo. O objetivo deste trabalho é efetuar uma revisao do estudo anatomopatológico original de 12 crianças com diagnóstico de enfisema lobar congênito, procurando, mediante método quantitativo, pesquisar a presença do aumento do número de alvéolos no ácido pulmonar. Método. Os autores realizaram um estudo caso-controle pareado pela idade. O número de alvéolos em cada ácino pulmonar foi pesquisado pela técnica da contagem radial de alvéolos. Para comparar as medidas obtidas nos casos e seus respectivos controles, utilizaram a prova U de Mann-Whitney Regressao linear avaliou a influência da idade sobre as medidas. Resultados. Encontraram um número elevado de alvéolos nos portadores de enfisema lobar congênito operados com idade inferior a 3 anos, um número semelhante entre as idade de 3 e 7 anos e um número diminuído a partir dessa idade. Na criança normal, ocorre um aumento no número de alvéolos com o aumento da idade. No enfisema lobar congênito, esse número se mantém praticamente constante, independente da idade. Conclusao. Os achados permitiram concluir que: o lobo polialveolar pode ser diagnosticado por um método simples e prático como a contagem radial de alvéolos, colaborando para diminuir a freqüência de casos de etiologia desconhecida, um número de alvéolos maior que o esperado para idade encontra-se associado ao enfisema lobar congênito no paciente (operado) antes dos 3 anos de idade e que, ao contrário do que ocorre no pulmao normal, no lobo acometido por enfisema lobar congênito nao ocorre aumento no número de alvéolos com o aumento na idade.

Discrimination between ethanol inhibition models in a continuous alcoholic fermentation process using flocculating yeast.

Discrimination between different rival models for describing the inhibitory effect of ethanol both on yeast growth and on fermentation was studied for a continuous process of alcoholic fermentation in a tower reactor with recycling of flocculating cells. Models tested include linear, parabolic, hyperbolic, exponential, and generalized nonlinear power-law types. The best expressions were identified under the criteria that all the kinetic parameters should assume acceptable values in a feasible range and should result in the best fit of the experimental data. The kinetic parameters were estimated from steady-state data of several sugar concentrations in feeding stream (S0 = 160, 170, 180, 190, 200 g/L), constant dilution rate (D = 0.2 h-1), recycle ratio (alpha = 13.6), and temperature (T = 30 degrees C). The best model for the yeast growth was of power-law type, whereas for the product formation the best model was of linear type. These models were able to reproduce the trends of the process variables satisfactorily.

Evaluation of drug interaction microcomputer software: an updated comparison.

Nine drug interaction microcomputer software programs were evaluated and compared using clinical and general ease of use criteria. Descriptions of major changes or additions since the last review are detailed. The ability to screen for drug interactions was based on recent drug-drug and drug-food interactions. Recommended programs based on three price ranges are suggested.

Survey of clinical pharmacokinetic software for microcomputers.

Twelve distributors of pharmacokinetic software programs for microcomputers were surveyed to determine scope of drug coverage; the pharmacokinetics models, methods, and equations used; hardware requirements including use of math coprocessor, random access memory (RAM) required, storage space, printer support and mouse use; software features including availability of windows, pull-down menus, context sensitive help, graphical representation of data, ability to export data including to ASCII file and ability to store patient data; availability of support including toll-free telephone numbers, 24-hour support and clinical consultations; costs; and frequency of updates.

Evaluation of patient counseling microcomputer software programs.

Five patient counseling drug information programs are evaluated using specific criteria definitions. This article compares the features and ratings of each program. The scope of drug coverage is found to be good to excellent. Most of the programs fared poorly in the timeliness of the database. Updates to the programs range from quarterly to undefined schedule. The ease of readability of all the programs is excellent. The inclusion of key components of information is determined to be good to excellent. The overall patient performance ratings are excellent for each of the programs. The programs are all competitively priced. All of the programs evaluated are easy to use. The only distinguishing feature among the programs is the format of the printed output.

Drug interaction microcomputer software evaluation: drug interaction facts on disk.

Drug Interaction Facts on Disk (DIF) was evaluated using general and specific criteria. The installation process, ease of learning and use, the user documentation, and the technical support were rated excellent. The scope of coverage, the quality of the clinical documentation, and overall clinical performance were also excellent. The frequency of updates is good. The program's clinical performance was compared to RxTriage and Drug Therapy Screening System using five recently reported drug interactions. The ability to screen for selected drug-food/nutrient interactions was also evaluated. Drug Interaction Facts is rated to be one of the better bargains in drug interaction software programs.

Evaluation of IV compatibility microcomputer software programs.

Four microcomputer software programs that contain IV compatibility information were evaluated using specific criteria for these programs. This article compares scope of coverage, quality of clinical documentation, frequency updates, and clinical performance for these programs. There are no excellent IV compatibility programs. Of the programs tested, Micromedex performed the best. Therapeutic Software is not considered a comprehensive IV compatibility program. IV-Check PC and Medicom Micro performed equally well.

Survey of pharmacy computer vendors--sources of clinical databases.

Ninety-nine pharmacy computer vendors were surveyed to determine the sources of their clinical data bases for drug-drug interactions, drug-food/nutrient interactions and IV compatibilities. Sixty-five percent of the vendors cited two drug-drug interaction software programs most frequently. These are Drug Therapy Screening System from Medi-span and RxTriage from First Data Bank. First Data Bank is also the most frequently cited source for the drug-food interactions and IV compatibility databases.

Evaluation of drug interaction microcomputer software: comparative study.

Twelve drug interaction microcomputer software programs were evaluated and compared using general and specific criteria. This article summarizes and compares the features, ratings, advantages, and disadvantages of each program. Features of an ideal drug interaction program are noted. Recommended programs based on three price ranges are suggested.

Drug interaction microcomputer software evaluation: PDR's drug interactions and side effects diskettes.

The PDR's Drug Interactions and Side Effects System was evaluated using general and specific criteria. The installation process, ease of learning, and ease of use were rated excellent. The user documentation and technical support were good. The quality of the clinical documentation was fair. The scope of coverage and overall clinical performance were fair. The frequency of updates is good. The primary advantage of the program is its citation of drug interactions and side effects listed in the official product labeling of numerous brand name products. The major disadvantages are that it lacks evaluative interaction information, may not include current information, and only contains brand names listed in one of the PDR compendia.

Drug interaction microcomputer software evaluation: Drug Therapy Screening System (DTSS).

Drug Therapy Screening System (DTSS) was evaluated using general and specific criteria. The installation process, ease of learning and use, the user documentation, and the technical support were rated excellent. The scope of coverage, the quality of the clinical documentation, and overall clinical performance were also excellent. The frequency of updates is good. The program is one of the best microcomputer drug interaction software packages evaluated by the authors thus far, because of its comprehensiveness, simplicity in use, and quality of its drug interaction information. The relatively high annual cost may limit its attractiveness.

Drug interaction microcomputer software evaluation: the Medical Letter Drug Interactions Program.

The Medical Letter Drug Interactions Program was evaluated using general and specific criteria. The installation process, ease of learning, and use were rated excellent. The user documentation and technical support were good. The quality of the clinical documentation was excellent. The scope of coverage and overall clinical performance were good. The frequency of updates is fair. The primary advantages of the program are low costs and fast, reliable screening tool for drug interactions.

Unit dose pharmacy workload forecasting: validation of the pharmacy service unit model.

Departmental efficiency is a priority issue for hospital administration as third party payers maintain or reduce the level of reimbursement. This study validates the PHASU (PHArmacy Service Unit) model, which predicts the workload and productivity of a unit dose pharmacy. A PHASU equivalency system enabled the authors to develop a comparative standard for all pharmacy procedures. The procedure most reflective of workload is unit dose orders. Predicted productivity and staff requirements compare favorably to management engineering determinations. The PHASU model represents a reliable workload forecasting instrument that pharmacy managers can prospectively incorporate in the support of current and future pharmacy services.

Drug interaction micromputer software evaluation: RxTriage.

RxTriage was evaluated using general and specific criteria. The installation process, ease of learning and use, and technical support were rated excellent. The user documentation was good. The scope of coverage, frequency of updates and overall clinical performance were good. The quality of the clinical documentation, which included key drug interaction texts and primary references, was excellent. The primary advantages of the program are the quality of its data base and interaction information and the inclusion of decision support tables. The disadvantage is the relative high cost as compared to other available microcomputer programs.