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Biomedical subjects

R Guzman

Publications and source records attributed to R Guzman.

At least 55 records · Page 3Linked to original sources
PubMed1996

Interferon alpha 2b as maintenance therapy in low grade malignant lymphoma improves duration of remission and survival.

We assessed the efficacy and toxicity of interferon alpha 2b (IFN) as maintenance therapy in patients with low grade malignant lymphoma. Between March 1986 and December 1989, 98 patients with low-grade malignant lymphoma in complete remission after conventional chemotherapy were randomly assigned to received IFN, 5.0 MU three times a week for one year, as maintenance therapy (n = 48), or to receive no treatment (control group, n = 50). In March 1994, the median duration of response had not yet been reached in the patients treated with IFN compared to 46 months in the control group. At 9-years 62% of the patients in the IFN arm remain in first complete remission compared to only 25% in the control group (p <.001). In addition, the median duration of survival has not yet been reached in either the IFN arm compared to 74 months in the control group (p <.001). Quality of life was excellent in both groups and severe side effects secondary to IFN treatment were not observed. All patients completed the planned dose of IFN. We conclude that IFN as maintenance therapy in low-grade malignant lymphoma is an excellent therapeutic option because it improves the duration of remission and survival without producing severe side effects or reducing the quality of life.

Adult↗
PubMed1996

Technetium-99m-pertechnetate uptake by intrathyroidal parathyroid adenoma.

A 57-yr-old woman was referred for preoperative scintigraphic localization of a parathyroid adenoma. Double-phase 99mTc-sestamibi imaging was performed followed by a separate-day [99mTc]pertechnetate thyroid scan. There was marked accumulation of both tracers by a right lower pole ¿thyroid' nodule which, at surgery, proved to be an intrathyroidal parathyroid adenoma. Hypervascularity is the presumed explanation for rare cases of pertechnetate-avid parathyroid adenomas.

Adenoma↗
PubMed1995

Preoperative localization of a parathyroid adenoma with Tc-99m sestamibi imaging in a patient with concomitant nontoxic multinodular goiter.

Preoperative localization of parathyroid adenomas is useful in patients undergoing parathyroidectomy. The authors report a patient with hyperparathyroidism and an associated nontoxic nodular goiter. Technetium-99m sestamibi scintigraphy localized and differentiated the parathyroid adenoma from the multinodular goiter. Excellent correlation was found between preoperative radionuclide imaging and surgical pathology. Technetium-99m sestamibi parathyroid imaging may be a simple and helpful test in the surgical management of parathyroid adenomas, particularly in patients with nontoxic multinodular goiter.

Adenoma↗
PubMed1995

Mammary phenotypic expression induced in epidermal cells by embryonic mammary mesenchyme.

The goal of this research was to establish methods for inducing mammary epithelial differentiation from nonmammary epithelium. For this purpose, mid-ventral or dorsal epidermis (skin epithelium; SKE) from 13-day rat or mouse embryos was associated with 13-day embryonic mouse mammary mesenchyme (mammary gland mesenchyme; MGM) (mouse MGM+rat or mouse SKE). The resultant MGM+SKE recombinants as well as controls (homotypic mouse mammary recombinants, homotypic mouse skin recombinants and mouse mammary mesenchyme by itself) were grafted under the renal capsule of syngeneic or athymic female nude mouse hosts. Most female hosts were induced to undergo lactogenesis by grafting an adult pituitary which elicited a state of hyperprolactinemia. Tissue recombinants of mouse MGM+rat or mouse SKE grown for 1 month in vivo formed a hair-bearing keratinized skin from which mammary ductal structures extended into the mesenchyme. The ducts were composed of columnar luminal epithelial cells as well as basal, actin-positive myoepithelial cells. When grown in pituitary-grafted hosts, the ductal epithelial cells expressed casein and alpha-lactalbumin as judged by immunocytochemistry. The expression of caseins in MGM+SKE recombinants was confirmed by Western blot. The epithelial cells in mouse MGM+rat SKE recombinants expressing milk proteins were shown to be rat cells while the surrounding connective tissue was composed of mouse cells based upon staining with Hoechst dye 33258. Using mammary-specific markers, these studies confirmed the earlier morphological studies of Propper and unequivocally demonstrated for the first time that embryonic mammary mesenchyme can induce morphological and functional mammary differentiation from nonmammary epithelium.

Animals↗
PubMed1992

Transgenes expressing the Wnt-1 and int-2 proto-oncogenes cooperate during mammary carcinogenesis in doubly transgenic mice.

The Wnt-1 and int-2 proto-oncogenes are transcriptionally activated by mouse mammary tumor virus insertion mutations in virus-induced tumors and encode secretory glycoproteins. To determine whether these two genes can cooperate during carcinogenesis, we have crossed two previously characterized lines of transgenic mice to obtain bitransgenic animals carrying both Wnt-1 and int-2 transgenes under the control of the mouse mammary tumor virus long terminal repeat. Mammary carcinomas appear earlier and with higher frequency in the bitransgenic animals, especially the males, than in either parental line. Nearly all bitransgenic males develop mammary neoplasms within 8 months of birth, whereas only 15% of Wnt-1 transgenic males and none of the int-2 transgenic males have tumors. In virgin bitransgenic females, tumors occur approximately 2 months earlier than in their Wnt-1 transgenic siblings; int-2 transgenic females rarely exhibit tumors. Preneoplastic glands from the bitransgenic animals of either sex demonstrate pronounced epithelial hyperplasia similar to that seen in Wnt-1 transgenic virgin females and males, and both transgenes are expressed in the hyperplastic glands and mammary tumors. RNA from the int-2 transgene is more abundant in mammary glands from bitransgenic animals than from int-2 transgenic animals; the increase is associated with high levels of RNA specific for keratin genes 14 and 18, suggesting that Wnt-1-induced epithelial hyperplasia is responsible for the observed increase in expression of the int-2 transgene.

Animals↗
PubMed1992

Developmental response of adult mammary epithelial cells to various fetal and neonatal mesenchymes.

Adult mouse mammary epithelial cells were isolated and grown in combination with mesenchyme from the following sources: embryonic preputial gland, foot skin, tail skin, genital tubercle skin, mammary gland, and neonatal uterus, vagina and urinary bladder. Following 1 month of in vivo cultivation of the tissue recombinants as grafts underneath the renal capsule of normal female or hyperprolactinaemic (pituitary-grafted) hosts, the specimens were analysed histologically and immunocytochemically for the expression of milk proteins, smooth muscle actin, and cytokeratins. Mesenchymal effects on adult mammary epithelium varied with the source of the mesenchyme and the hormonal status of the host. In normal female hosts preputial gland mesenchyme induced extensive mammary epithelial growth and ductal branching morphogenesis with epithelial differentiation and ductal pattern being comparable to that observed in homotypic recombinants composed of mammary gland mesenchyme plus adult mammary epithelium. Other mesenchymes (from foot, tail, genital tubercle and uterus) preserved ductal morphology and normal epithelial differentiation, but elicited minimal epithelial growth and branching morphogenesis in adult mammary epithelium. In association with urogenital sinus, vaginal or bladder mesenchymes ductal branching morphogenesis of the mammary epithelium was absent or greatly distorted and the epithelium exhibited a stratified cuboidal phenotype even though considerable epithelial growth had occurred. In hyperprolactinaemic hosts (which received a pituitary graft) epithelial growth, alveolar morphogenesis, and synthesis of casein and milk fat globule protein was stimulated in all tissue recombinants although to different extents. Alveolar morphogenesis and milk protein expression were extensive in tissue recombinants prepared with mesenchyme from embryonic mammary gland, preputial gland, tail skin and urinary bladder, but were minimal in tissue recombinants prepared with foot or genital tubercle skin. Few milk-protein-positive alveoli formed in tissue recombinants composed of mammary epithelium combined with urogenital sinus or vaginal mesenchyme, even following growth in pituitary-grafted hosts. These findings demonstrate: (1) that adult mammary epithelial cells are responsive to the growth-promoting influences of heterotypic embryonic and neonatal mesenchymes; (2) that mammary growth and branching morphogenesis are induced to variable extents by different mesenchymes; (3) that fibrous (non-adipose) mesenchymes are effective inducers of mammary epithelial development; and (4) that the ability to form alveoli and produce milk proteins in adult mammary epithelial cells is critically dependent upon the nature of the connective tissue environment.

Animals↗
PubMed1991

Etiology of prosthetic anastomotic false aneurysms: pathologic and structural evaluation in 26 cases.

To determine the etiology of anastomotic false aneurysms (AFAs), 26 textile graft specimens, removed because of AFA, were studied morphologically, histologically and by scanning electron microscopy. No cases of suture-related failures leading to AFA were found. Nine cases of frayed grafts were documented but were not the cause of AFA formation. In three cases, chemical degradation of the fibres, which may have been secondary to lipid infiltration, may have contributed to AFA formation. There were no cases of overt clinical infection, but the presence of bacteria was documented by scanning electron microscopy in 20 cases. The role of bacteria is not well defined, but they may be a factor in host arterial-wall degeneration as a cause for AFA formation.

Adult↗
PubMed1990

[Hodgkin's disease treated with chemotherapy at reduced dosage].

Fifty-six patients with Hodgkin's disease in advanced stages (III-IV) were entered in a study aimed to compare standard doses (28 cases) with low doses (28 cases) ABVD regimen. Both groups had similar clinico-pathological features. The group receiving standard doses chemotherapy achieved complete remission rate of 89% versus 85% for the low-doses group. The number of relapses was, respectively, 8 and 9, and the duration of remission was 66 and 57 months, respectively. Presently, 24 patients have died, 11 of the standard doses group and 13 of the reduced doses group. Toxicity was notably higher in the group receiving standard dosage, where fatal myelosuppression was present in two instances. Those data appear to suggest that chemotherapy with reduced doses for Hodgkin's disease can attain similar response rate and survival than those achieved with standard treatment, with the advantages of a lower toxicity.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Odontodysplasia in a pediatric patient: literature review and case report.

A case of a three-year-old Caucasian male with odontodysplasia is presented. Although the etiology of this condition is unknown, this anomaly involves both the mesodermal and ectodermal dental components and results in deficient and abnormal formation of dentin and enamel. The orofacial characteristics and dental findings of the condition are presented in this case report.

Child, Preschool↗
PubMed1990

Human umbilical vein grafts as infrainguinal bypasses: long-term clinical follow-up and pathological investigation of explanted grafts.

This retrospective study examines 105 consecutive infrainguinal bypasses using human umbilical vein (HUV) grafts as blood conduits over a 9 year period. In addition, 39 segments of these grafts were harvested at reoperation and submitted for morphologic, histologic, and scanning electron microscopy examinations. Fifty-two below-knee femoro-popliteal and 53 femoro-distal bypasses were performed in 93 patients. Sixty-seven per cent of these bypasses were performed for either rest pain (18%) or gangrene (49%) and 29% were performed for acute ischemia. Primary and secondary patency rates were not statistically different and were 38% and 29% at 1 and 3 years respectively. Factors found to have a significant effect on patency were site of distal anastomosis, state of distal run-off, and indication for operation. Other complications requiring reoperation included aneurysm formation (8 cases), infection (6 cases), mural thrombus (2 cases), and stenosis (2 cases). Pathologic examination revealed a damaged luminal surface in 22 grafts, deep folds in 8 grafts and delamination of the graft wall in 16 cases. Bacteria were seen in the folds of the grafts and, in addition, the presence of bacteria was documented in 7 out of 26 clinically non-infected grafts. The combination of poor patency rates and pathologic evidence of biodegradative phenomena have led us to discontinue HUV as an arterial substitute.

Adult↗
PubMed1990

Femorodistal bypass using the chemically processed human umbilical vein graft: 9-year experience.

To evaluate patency, limb salvage rates and complications associated with the use of human umbilical vein as an arterial substitute, the authors carried out a retrospective review of 52 femorodistal bypasses performed over 9 years using human umbilical vein. Indications for operation included acute ischemia, rest pain and nonhealing ulceration or gangrene. There were 28 early occlusions, which resulted in a 1-month primary patency rate of 46% and a secondary patency rate of 52%. The primary and secondary patency rates at 1 year were 18% and 19% respectively. The mean limb salvage rate at 1 month was 57% and at 1 year 34%. Three aneurysms occurred (two anastomotic, one graft). Factors found to have a significant effect on patency rates were indication for operation and state of distal runoff. Infection occurred in 6% of grafts and led to amputation in every case. These disappointing results have caused the authors to discontinue use of human umbilical vein as an arterial substitute.

Adult↗
PubMed1989

An histo-morphological evaluation of ninety surgically excised human umbilical vein grafts.

Morphological, histological, and scanning electron microscopy examinations were performed on 90 surgically excised human umbilical vein grafts. Most of the explanted grafts were removed because of thrombosis or infection and were removed typically from a patient in the mid 60s and after an average duration of implantation of 11 months. Multiple structural defects were found including deep folds, breaks on the luminal surface, and delamination. These areas as well as anastomotic sites represented potential areas for thrombotic accumulation. A higher incidence of infection was observed in grafts composed of 2 or 3 segments. Bacteria were often found in folds and could be seen invading the wall of the prosthesis. In addition, bacteremic colonization was often seen in noninfected grafts. The late aneurysmal formations were also of particular concern. The biodegradation of the wall and the disruption of the polyester mesh were the probable causes. The second generation Dardik Biograft aimed at reducing these formations. The success of this new processing remains to be evaluated.

Adult↗
PubMed1989

Thyroid function in neonates from goitrous and nongoitrous iodine-sufficient areas.

We compared thyroid function between newborns from goitrous and nongoitrous localities in which iodine intake has been supplemented since 1955. Cord serum samples were analyzed in 185 infants born during a 9-month period (1986-1987) in 2 goitrous and 1 nongoitrous localities of western Colombia. Urinary iodine was determined in all mothers before delivery. No significant differences were found among neonates of the 3 localities (Kruskal-Wallis test) for the various thyroid hormone values, and all values were within the normal range, although there was a trend in distribution of TSH to higher values in both goiter areas. Thyroid autoantibodies (antithyroglobulin and antithyroid microsomal) were negative in all neonates, and iodine intake, as indicated by urinary iodine, was adequate and similar among the mothers of the 3 groups. Those newborn infants with serum TSH values higher than 20 mU/L were reexamined 5-7 months later. At this time, all infants had lower serum TSH values and their serum free T4 index and T3 values were normal. Gestational age, weight, and height at birth were normal and also equal among the neonates in the 3 localities. These results indicate that neonates from goitrous iodine-sufficient areas have thyroid function similar to that of infants born in nongoitrous areas equally supplemented with iodine, and therefore, they are not more at risk to develop congenital hypothyroidism.

Colombia↗
PubMed1989

Biologic and structural evaluation of 80 surgically excised human umbilical vein grafts.

Human umbilical vein is a valuable alternative to autogenous saphenous vein in lower-limb revascularization. However, the long-term patency is not as good. To understand better the reasons for this, the authors studied the biologic and structural changes occurring in 80 segments of human umbilical vein (HUV) grafts excised from 70 patients. Morphologic, histologic and scanning electron microscopy examinations were performed on each specimen. It was noted that increasing duration of implantation was associated with greater encapsulation and less surrounding inflammatory reaction. Twenty-six percent of clinically noninfected grafts were found to harbour bacteria. Bacteremic colonization was often in the folds of the luminal surface. As a result of these findings, the authors emphasize the need for complete excision of clinically infected grafts. Anastomoses between HUV segments are discouraged because they are associated with a high frequency of infection and a corresponding decrease in duration of implantation. Delamination of the wall was common, and such sites may represent areas at risk for further degradation. Continued surveillance of the biologic and structural changes occurring in excised grafts remains an important method in increasing our understanding of the evolutive complications of HUV grafts.

Adult↗
PubMed1988

Affinity surfactants as reversibly bound ligands for high-performance affinity chromatography.

Pyridine was coupled covalently to a nonionic ethoxylated alcohol: octaethylene glycol n-hexadecyl ether. This modified surfactant was found to be a reversible, competitive inhibitor of horse serum cholinesterase. The surfactant bound irreversibly, in aqueous media, to octadecyl-bounded reverse phase silica particles commonly used for high-performance liquid chromatography. The amount of ligand bound was found to be 550 mumol/ml of packing, a concentration that is over 100 times higher than what can be normally bound to agarose affinity chromatography supports. With this packing, a 280-fold purification of cholinesterase from horse serum and a 79-fold purification of human serum cholinesterase were accomplished, with yields greater than 80%, using a 2-cm-long column and a 7-min elution time. The affinity surfactant could be eluted from the column using a 6:4 (v/v) mixture of methanol and isopropanol. This technique should be generally applicable in the development of biospecific supports for high-performance affinity chromatography.

Animals↗