Thesis (M.S.)--University of Louisville, 2005. / School of Medicine, Department of Pharmacology and Toxicology. Vita. "May 2005." Includes bibliographical references (leaves 106-118).

Thesis (B.A.)--Haverford College, Dept. of Psychology, 2008. / Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2006. / Full text release at OhioLINK's ETD Center delayed at author's request

The first workers to use the isolated perfused rat liver for the study of gluconeogenesis were Corey and Britton (1941). Subsequently, other investigators found the modified method of Miller et al (1951) to be more suitable. This technique, with modifications introduced by Mortimore (1961) and Hems et al (1966) was used in the present study. The isolated liver is perfused through the portal vein with saline, supplemented by bovine serum albumin and washed human erythrocytes, under a pressure of about 20cm of water, maintained by a reservoir of adjustable height. The perfusate which passes through the liver enters the inferior vena cava and passes, via a cannula, to a collecting vessel from which it is pumped to the top of a multiple bulb oxygenator and then returned to the liver for re-perfusion. This technique has proved to be a satisfactory means of assessing changes in the metabolic status of hepatic cells in response to starvation and exposure to halothane. The study described here was performed to determine whether the isolated liver perfusion technique can be used to measure the effects on liver perfusion of therapeutic and supratherapeutic doses of various drugs, some of which have been reported to affect liver metabolism adversely in the intact animal. Liver function was assessed by studying gluconeogenesis and bromosulphthalein clearance. Alcohol and hexane were administered in toxic doses, rifampicin and isoniazid in high doses and paracetamol in therapeutic doses. Inbred male Wistar rats were used for these studies. Hexane was injected subcutaneously, while the other drugs were given per os on 7 consecutive days each week for a period of 90 days; with the exception of the control group in the hexane study, all the control groups were untreated. Pyruvate, a precursor for gluconeogenesis (synthesis of glucose from non-carbohydrate sources) is an excellent substrate for the formation of oxaloacetate, which is probably an obligatory intermediate in the pathway to glucose synthesis. It has been used over a number of years by different investigators who have .studied gluconeogenesis using the isolated liver perfusion technique. It was used for the same purpose in the present study. Methylene blue, a redox dye, capable of oxidising NADH to NAD+, was used to determine whether an altered NADH : NAD+ ratio would have any effect on the output of glucose in the ethanol, paracetamol and hexane studies. Fructose, a non-NAD+ dependent precursor of glucose. was also used for this purpose in the ethanol study. All the drugs studied were found to inhibit gluconeogenesis. This was shown by a decrease in glucose levels and an increase in lactate : pyruvate ratios in the perfusion medium of experimental livers. The decreased glucose production by the experimental livers, which occurred pari passu with an increased pyruvate utilization, indicates that in these animals pyruvate was used for the production of other compounds such as lactate. In contrast. glucose production and pyruvate utilization were increased in the control group indicating that pyruvate was used mainly for the production of glucose. In the ethanol group, impaired gluconeogenesis was probably due to a change in the NADH : NAD+ ratio; when methylene blue was introduced into the perfusion medium of this group the output of glucose was high. Impaired gluconeogenesis in the paracetamol and hexane-treated groups was probably related to the non-availability of oxaloacetate or impairment of the activity of key enzymes involved in gluconeogenesis; when methylene blue was added to the perfusion medium of these animals the glucose output remained low. Except for the rifampicin study. bromosulphthalein clearance was impaired in all the experimental groups. Histological examination of liver tissue obtained from the hexane-treated animals demonstrated severe fatty change. In conclusion, these studies have demonstrated that the isolated liver perfusion technique is a suitable method of evaluating the effect of therapeutic and supra-therapeutic doses of some drugs which affect hepatic function. Ethanol, isoniazid, rifampicin, paracetamol (in therapeutic doses) and hexane were found to alter liver function as evidenced by impaired gluconeogenesis and bromosulphthalein clearance. In addition, histological evidence of liver damage was noted in rats treated with hexane. / Thesis (M.Med.Sc.)-University of Natal, Durban, 1988.

Thesis (MSc.(Pharmacology)--Faculty of Health Sciences)-University of Pretoria, 2008.

Beta blockers are commonly prescribed for the chronic treatment of hypertension, one of the most prolific disease states worldwide. The beta blockers selected for this study include acebutolol hydrochloride, labetalol hydrochloride, metoprolol tartrate oxprenolol hydrochloride and propranolol hydrochloride. All of these compounds have a short elimination half-life, necessitating multiple dose per day regimens and therefore the development of sustained release dosage forms incorporating these agents was considered beneficial in terms of extending the dosing interval, with the aim of improving patient compliance and subsequent therapeutic outcomes. Preformulation studies that were conducted included moisture content analysis by Karl Fischer titration, and DSC, a method used to predict potential interactions between the drugs and tablet excipients. Tablets were manufactured by both wet granulation and direct compression techniques, and the resultant drug release characteristics were evaluated using the USP Apparatus 3(BIO.DIS). A validated isocratic HPLC method, capable of separating the five drug candidates simultaneously, was developed and used for the analysis of drug samples. Tablet quality was assessed using analyses that included the physical assessment of weight, diameter, thickness, hardness and friability, as well as content uniformity of tablets, before and after dissolution testing. Direct compression tablet formulations containing each of the five beta blockers were successfully adapted from a prototype wet granulation matrix tablet containing metoprolol tartrate, and various formulation variables were investigated to establish,their effect on the rate and extent of drug release from these tablets. The grade and quantity of ethylcellulose used in the wet granulation and direct compression formulae influenced the release rate of some drug candidates. In addition, an alternative formulation method, involving freeze-drying of the drug with an ethylcellulose dispersion, was shown to have potential for altering release rates further. Anti-frictional agents, talc and colloidal silicon dioxide, did not affect drug release from these matrices,however, they affected the physical character:istics such as tablet weight and thickness, of the resultant tablets. All of the matrix tablets formulated were shown to release drug according to square root of time kinetics, in a sustained manner over a 22 hour period.

In this study, we aimed to develop new membranes based on chitosan (CHIT) and fish scale (ESC). The possibility of using the uncrosslinked membranes (ESC/CHIT) and sodium tetraborate-crosslinked membranes (ESC/CHIT-B) for tetracycline (TCC) and doxocicline (DOX) release was investigated. The drugs releases were studied at 30 and 37º C in phosphate buffered saline (pH 7.4). The ESC/QUIT membranes released lower amounts of the drugs for shorter intervals of time in relation to ESC/QUIT-B. The in vitro releases profiles of TCC and DOX from synthesized membranes were all well fitted to the Peppas model. The releases of DOX from the crosslinked and the uncrosslinked membranes were regarded to a coupled diffusion/ polymer relaxation mechanism. This mechanism was also responsible for the release of TCC from ESC/QUIT, whereas polymer relaxation alone controlled the release of TCC from ESC/CHIT-B. The results suggest that the synthesized membranes are promising for application in drug delivery systems / Neste estudo, buscou-se desenvolver novas membranas à base de quitosana (QUIT) e escama de peixe (ESC). A possibilidade de utilização das membranas não reticuladas (ESC/QUIT) e membranas reticuladas com tetraborato de sódio (ESC/QUIT-B) para a liberação dos fármacos tetraciclina (TCC) e doxociclina (DOX) foi avaliada. A liberação dos fármacos foi estudada em tampão fosfato salino (pH 7,4) a 30 e 37ºC. As membranas ESC/QUIT liberaram menores quantidades dos fármacos durante intervalos de tempos mais curtos em relação à ESC/QUIT-B. Os dados de liberação in vitro da TCC e DOX a partir das membranas preparadas ajustaram-se bem ao modelo de Peppas. As liberações da DOX a partir de membranas reticuladas e não reticuladas foram controladas por mecanismos de difusão e de relaxação polímérica. Este último mecanismo também foi responsável pela liberação da TCC a partir de ESC/QUIT, enquanto que somente a relaxação polimérica controlou majoritariamente a liberação da TCC a partir de ESC/QUIT-B. Os resultados obtidos sugeriram que as membranas preparadas são promissoras para aplicação em sistemas de liberação de fármacos.

A lesão do nervo periférico resulta em dor neuropática persistente ou crônica, caracterizada por dor espontânea em queimação, acompanhada de alodinia e hiperalgesia. A ocorrência de alterações patológicas no sistema nervoso periférico e na medula espinal contribui para o desenvolvimento da dor neuropática. Estas alterações incluem descargas ectópicas nas fibras nervosas periféricas lesadas, as quais mantêm os impulsos nervosos aferentes para o sistema nervoso central. Várias substâncias sintetizadas e/ou liberadas durante o processo inflamatório tais como cininas, neuropeptídeos, citocinas, óxido nítrico, entre outros, assim como as alterações morfofuncionais celulares, podem interferir com a atividade dessas fibras. Estas alterações na homeostasia do indivíduo podem implicar em uma perda da qualidade de vida do paciente. Portanto, tais informações são essenciais para o auxílio de uma terapia analgésica eficiente e/ou preventiva. Assim, o presente projeto tem como objetivo compreender melhor a participação das isoformas neuronal e induzível em modelo de dor neuropática induzida pela lesão constritiva crônica do nervo isquiático de ratos. Para tanto, foi avaliada a sensibilidade dolorosa dos animais utilizando inibidor seletivo para NOS neuronal (nNOS) e induzível (iNOS), antes e após os testes comportamentais. Avaliamos também a distribuição das isoenzimas da NOS, na medula espinal e gânglios da raiz posterior, pelo método de imuno-histoquímica. Ainda, separadamente, analisou-se a síntese de nNOS e iNOS, pelo método de Western blot, e a presença de óxido nítrico utilizando marcador fluorescente DAF-2 (DA). Tais investigações poderão contribuir fornecendo base científica para o desenvolvimento de novos medicamentos e por elucidar alguns dos mecanismos de ação do óxido nítrico, envolvidos na dor neuropática, que é de difícil tratamento e de grande relevância clínica. / The peripheral nerve injury results in persistent or chronic neuropathic pain characterized by spontaneous burning pain accompanied by allodynia and hyperalgesia. The occurrence of pathological changes in the peripheral nervous system and spinal cord contributes to the development of neuropathic pain. These changes include ectopic discharges in damaged peripheral nerve fibers, which maintain the afferent nerve impulses to the central nervous system. Many substances synthesized and / or released during inflammation such as neuropeptides, cytokines, nitric oxide, among others, as well as cellular morphofunctional changes, may interfere with the activity of those fibers. These changes in the homeostasis of the individual can result in a loss of quality of life of the patient. Therefore, such information is essential for an effective analgesic therapy and / or preventive. The aims of this project are to better understand the involvement of neuronal and inducible isoforms in a model of neuropathic pain induced by chronic constriction injury in sciatic nerve of rats. We evaluated the pain sensitivity of animals using a selective inhibitor for neuronal (nNOS) and inducible (iNOS) NOS. We also evaluate the distribution of NOS isoenzymes in the spinal cord and dorsal root ganglia, by the method of immunohistochemistry. Separately, we analyzed the synthesis of iNOS and nNOS by Western blot assay, and the presence of nitric oxide using fluorescent probe DAF-2 (DA). Such research could contribute to providing scientific basis for the development of new drugs and to elucidate some of the mechanisms of action of NOS involved in neuropathic pain.

A lesão do nervo periférico resulta em dor neuropática persistente ou crônica, caracterizada por dor espontânea em queimação, acompanhada de alodinia e hiperalgesia. A ocorrência de alterações patológicas no sistema nervoso periférico e na medula espinal contribui para o desenvolvimento da dor neuropática. Estas alterações incluem descargas ectópicas nas fibras nervosas periféricas lesadas, as quais mantêm os impulsos nervosos aferentes para o sistema nervoso central. Várias substâncias sintetizadas e/ou liberadas durante o processo inflamatório tais como cininas, neuropeptídeos, citocinas, óxido nítrico, entre outros, assim como as alterações morfofuncionais celulares, podem interferir com a atividade dessas fibras. Estas alterações na homeostasia do indivíduo podem implicar em uma perda da qualidade de vida do paciente. Portanto, tais informações são essenciais para o auxílio de uma terapia analgésica eficiente e/ou preventiva. Assim, o presente projeto tem como objetivo compreender melhor a participação das isoformas neuronal e induzível em modelo de dor neuropática induzida pela lesão constritiva crônica do nervo isquiático de ratos. Para tanto, foi avaliada a sensibilidade dolorosa dos animais utilizando inibidor seletivo para NOS neuronal (nNOS) e induzível (iNOS), antes e após os testes comportamentais. Avaliamos também a distribuição das isoenzimas da NOS, na medula espinal e gânglios da raiz posterior, pelo método de imuno-histoquímica. Ainda, separadamente, analisou-se a síntese de nNOS e iNOS, pelo método de Western blot, e a presença de óxido nítrico utilizando marcador fluorescente DAF-2 (DA). Tais investigações poderão contribuir fornecendo base científica para o desenvolvimento de novos medicamentos e por elucidar alguns dos mecanismos de ação do óxido nítrico, envolvidos na dor neuropática, que é de difícil tratamento e de grande relevância clínica. / The peripheral nerve injury results in persistent or chronic neuropathic pain characterized by spontaneous burning pain accompanied by allodynia and hyperalgesia. The occurrence of pathological changes in the peripheral nervous system and spinal cord contributes to the development of neuropathic pain. These changes include ectopic discharges in damaged peripheral nerve fibers, which maintain the afferent nerve impulses to the central nervous system. Many substances synthesized and / or released during inflammation such as neuropeptides, cytokines, nitric oxide, among others, as well as cellular morphofunctional changes, may interfere with the activity of those fibers. These changes in the homeostasis of the individual can result in a loss of quality of life of the patient. Therefore, such information is essential for an effective analgesic therapy and / or preventive. The aims of this project are to better understand the involvement of neuronal and inducible isoforms in a model of neuropathic pain induced by chronic constriction injury in sciatic nerve of rats. We evaluated the pain sensitivity of animals using a selective inhibitor for neuronal (nNOS) and inducible (iNOS) NOS. We also evaluate the distribution of NOS isoenzymes in the spinal cord and dorsal root ganglia, by the method of immunohistochemistry. Separately, we analyzed the synthesis of iNOS and nNOS by Western blot assay, and the presence of nitric oxide using fluorescent probe DAF-2 (DA). Such research could contribute to providing scientific basis for the development of new drugs and to elucidate some of the mechanisms of action of NOS involved in neuropathic pain.