Biomedical subjects

G Jacobs

Publications and source records attributed to G Jacobs.

At least 73 records · Page 4Linked to original sources

PubMed1989

Electrical pulse train and single pulse stimulation of the small intestine: acute and chronic studies in the dog.

In vitro tests have shown that electric currents may lead either to relaxation or contraction of the bowel wall. Because voluntary changes of the intestinal motility could be useful in the treatment of intestinal disorders, we investigated the reactions elicited by electrostimulation of the small intestine in the intact animal. Stimulating electrodes, electroenteromyogram electrodes, and pressure monitoring tubes were used to instrument a 5-cm segment of the proximal jejunum in five dogs in acute studies and in two dogs in chronic studies. Single pulses of 200 ms elicited a pulsatile pressure increase of 10-35 mm Hg. Pulse train stimulation was followed by a more complex reaction. Trains of 500-microseconds, 910-Hz pulses at 30 mA evoked a 50-80 mm Hg pressure increase, 1-ms, 10-Hz trains caused an initial relaxation, followed by a pressure increase during stimulation and a further pressure increase after termination of the burst. These reactions were similar to those observed by Campbell working with colon in vitro. The chronic fasted animals reacted to 500 microseconds, 910-Hz, 25-mA stimulation with a mean pressure increase of 26 mm Hg (n = 10) and to 200-microseconds, 1.67-kHz, 30 mA stimulation with 28 mm Hg (n = 16). In the fasted animals a pressure increase during stimulation predominated (Campbell type I), whereas in the fed animal an additional off response after termination of the stimulation was the most common type of reaction (Campbell type II). Initial relaxation (Campbell type III) could be elicited by 1-ms, 10-Hz trains.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Dynamic rehabilitation of the paralyzed face--II. Electronic control of the reinnervated facial musculature from the contralateral side in the rabbit.

This work is the continuation of a previous pilot study in the rabbit in which motion originating on the face was picked up by miniature strain gages and channeled synchronously to strap muscles reinnervated via crossover nerve-muscle pedicles. In the current series of experiments, we modified the distal limb of the system to reinnervate the previously paralyzed opposite side of the face via an ansa hypoglossi nerve--thyrohyoid muscle pedicle in five animals. Muscular contraction was induced on the intact side by stimulating different branches of the facial nerve, and corresponding information was channeled to the reinnervated side through an upgraded electronic stimulator via monopolar electrodes placed around the nerve pedicle in the neck. In addition to demonstrating perfect synchrony between intact and reinnervated sides, this facial stimulator allowed the reinnervated side of the face to follow the intact side in a graded and sustained fashion, thus demonstrating that fine tuning of reinnervated facial musculature was possible.

Animals↗

PubMed1989

Effect of clindamycin on factor-VII activity in healthy cats.

Four healthy cats were given clindamycin orally in daily doses of 25 or 50 mg/kg of body weight for 6 weeks. Significant change in Factor-VII activity was not found, compared with pretreatment values. In 2 cats tested, toxin produced by Clostridium difficile was not detected in fecal samples obtained before treatment and at 6 weeks after treatment, suggesting that intestinal overgrowth by C difficile did not develop. Results of the study seemed to indicate that orally administered clindamycin does not measurably reduce synthesis of vitamin K-dependent clotting factors in healthy cats.

Animals↗

PubMed1988

Osteogenic sarcoma. Malignant fibrous histiocytoma subtype.

A distinctly different entity from the now well-delineated malignant fibrous histiocytoma (MFH) of bone is the MFH histopathologic subtype of osteogenic sarcoma. Although uncommon, recently the authors have encountered six cases of this neoplasm, in each of which the soft tissue component was devoid of bone elements and was microscopically indistinguishable from MFH of bone or soft tissue. Neoplastic osteoid and woven bone were present in the osseous component of each tumor, however. Radiologically, the lesions generally were osteoblastic but focally osteolytic with features typical of osteogenic sarcoma. Pain was the most common presenting symptom. There was no age or sex predilection. Immunocytochemical staining showed strong positivity with alpha-1-antichymotrypsin within malignant bizarre giant cells and occasional neoplastic osteoblasts in five cases. The biological behavior followed a very aggressive course. Four of the six patients developed pulmonary metastases 6 to 12 months after initial surgery; one patient presented initially with pulmonary metastases. Adequate tumor sampling as well as optimal correlation with clinical and radiographic information are required to distinguish the MFH subtype of osteogenic sarcoma from MFH of bone, both being high-grade neoplasms, however.

Adolescent↗

PubMed1988

Neurologic manifestations associated with hypothyroidism in four dogs.

Hypothyroidism was believed responsible for peripheral and central neurologic abnormalities in 4 dogs. Clinical signs consisted of abnormalities of gait and postural reactions and dysfunction of multiple cranial nerves in all 4 dogs. Circling, hypermetria, and spontaneous verticle nystagmus were observed in some of the dogs. Hypothyroidism was diagnosed in all 4 dogs on the basis of low resting serum thyroxine concentration and inadequate response to thyroid stimulating hormone. After thyroid hormone supplementation, resolution of neurologic abnormalities was complete in 2 dogs and partial in the other 2 dogs.

Animals↗

PubMed1988

Colliculus seminalis as a cause of a urethral filling defect in two dogs with Sertoli cell testicular neoplasms.

A urethral filling defect in the proximal portion of the pelvic urethra, suggestive of a mass, was detected by positive-contrast retrograde urethrography in 2 dogs with prostatic disease and Sertoli cell neoplasms. Extension of prostatic neoplasia into the urethra or primary urethral neoplasia were considered as explanations for the radiographic finding of an intraluminal filling defect in the pelvic urethra. Masses were visualized and biopsied during prostatic surgery. Masses were nonneoplastic and represented enlargement of the colliculus seminalis.

Animals↗

PubMed1988

Hemoglobin spherulosis in the vitreous cavity.

A 50-year-old woman was evaluated for a subretinal hemorrhage that extended into the vitreous of the right eye. Examination showed multiple refractile brown spherules in the vitreous. A vitrectomy was performed, and pathologic examination of the spherules showed them to be composed of free hemoglobin. Free-hemoglobin spherulosis in the vitreous, like cholesterosis bulbi, is a manifestation of vitreous hemorrhage.

Eye Diseases↗

PubMed1988

Voluntary control of an ileal pouch by coordinated electrical stimulation. A pilot study in the dog.

Ileal reservoirs were constructed in four dogs under general anesthesia and stimulated by means of a constant current generator that produced pulse trains at frequencies between 6 Hz and 1.67 kHz. Stimulation at 6 Hz with 50 ms pulses between amplitudes of 15 and 25 mA uniformly produced pouch contraction and reservoir emptying. Stimulation at other frequencies did not cause pouch emptying although pressure increases were sometimes observed. Such electrical stimulation may be useful for voluntary control of intestinal reservoirs when used as replacement for urinary bladder or colon. The mechanism by which the intestinal contraction is produced appears to be different than that produced by slow wave pacing.

Anastomosis, Surgical↗

PubMed1988

Chorioretinal lesions in chronic granulomatous disease of childhood. Clinicopathologic correlations.

The authors examined an eye obtained post-mortem from a patient with chronic granulomatous disease of childhood and clinically apparent chorioretinal scars. Histologic examination disclosed numerous chorioretinal scars with associated retinal pigment epithelial changes and glial proliferation. Special stains for bacteria and fungi were negative. Additional findings were scattered pigment-containing macrophages found in the patient's spleen, liver, lymph nodes, bone marrow, lungs, kidney, thymus, choroid, and retina. The significance of the pigmented macrophages is unknown, however they may represent an abortive macrophage response to infectious agents.

Adolescent↗

PubMed1988

Morphological effects of pyronaridine on malarial parasites.

The ultrastructural changes caused by a new antimalarial drug, pyronaridine, were investigated using mice infected with erythrocytic forms of Plasmodium berghei and P. falciparum cultivated in vitro in human erythrocytes. The first changes observed in both parasites after exposure to pyronaridine occurred in the food vacuoles. This suggests that the target organelle of this drug may be the food vacuole of malarial parasites. In addition, rapid alterations were also noted within the pellicular complex of both plasmodia.

Animals↗

PubMed1988

Glomerulopathy in squirrel monkeys with acute Plasmodium falciparum infection.

The renal pathology of 9 squirrel monkeys (Saimiri sciureus) with acute Plasmodium falciparum infection was studied by light and electron microscopy. Endocapillary proliferative glomerulonephritis was the major pathological change observed. The peroxidase anti-peroxidase method demonstrated the presence of IgG, IgM, and P. falciparum antigens in the mesangium and basement membrane. These findings were consistent with those seen in humans with acute P. falciparum infection and indicates that squirrel monkeys are likely to be a good model for the study of renal pathology in malaria research.

Acute Disease↗

PubMed1988

Bronchial carcinoid tumor with amyloid stroma.

The histopathologic, immunohistochemical, and ultrastructural findings of a unique case of an atypical bronchial carcinoid tumor containing abundant stromal amyloid are presented. The differential diagnosis from other neuroendocrine tumors that can produce amyloid is discussed.

Aged↗

PubMed1988

Multiple regression analysis, using body size and cardiac cycle length, in predicting echocardiographic variables in dogs.

A significant (P less than 0.0001) positive correlation was demonstrated between left ventricular internal chamber dimension in diastole or systole and body weight, body surface area, cycle length, and the square root of cycle length. On the basis of adjusted coefficients of determination, multiple regression analysis, using body weight or body surface area and cycle length or the square root of cycle length, was superior to separate simple regression with these variables in accounting for variations in left ventricular internal chamber dimensions. Shortening fraction had a significant (P less than 0.0001) negative correlation and left ventricular free wall measurements had a significant (P less than 0.0001) positive correlation to body weight and body surface area. For these echocardiographic variables, correlation to the square root of cycle length was insignificant (P greater than 0.05), and a multiple regression model was not helpful in developing confidence intervals. Septal wall measurements were not correlated with body weight, body surface area, cycle length, or the square root of cycle length.

Animals↗

PubMed1988

Influence of alterations in heart rate on echocardiographic measurements in the dog.

M-mode echocardiograms were recorded from 10 conscious, clinically normal dogs at various heart rates during atrial pacing. Heart rate was recorded as cycle length (seconds), and measurements were made only during sustained 1:1 atrial-to-ventricular conduction. In all dogs studied, there was a significant (P less than 0.01) positive correlation of left ventricular internal chamber dimension in diastole and systole to cycle length. Also, there was positive correlation between these left ventricular dimensions and the square root of cycle length, which predicted a plateau in dimensional changes as cycle length increased. Echocardiographic shortening fraction and left ventricular and septal wall thickness measurements did not change consistently during pacing. We concluded that left ventricular chamber dimensions in the dog may be significantly affected by alterations in heart rate.

Animals↗

PubMed1987

Complete interruption of the aortic arch in a dog.

Complete interruption of the aortic arch was diagnosed by angiocardiography in a dog with exercise intolerance, a cardiac murmur, polycythemia, and cardiomegaly. The defect was accompanied by a patent ductus arteriosus, ventricular septal defect, and subaortic stenosis. The dog was euthanatized, and the clinical diagnosis was documented by gross dissection of the heart. The site of aortic interruption was between the left carotid and left subclavian arteries, which is the most common location in human beings. The similarity with the pathologic findings of interrupted aortic arch in human beings suggests a similar mechanism responsible for the abnormal cardiac morphogenesis. The defect may be confused with other cardiac anomalies that can result in exercise intolerance, polycythemia, and cardiac murmur. This defect is amenable to surgical treatment, which emphasizes the importance of a correct anatomic diagnosis in clinical patients.

Animals↗

PubMed1987

The reactivity of galactose oxidase with snail galactans, galactosides and D-galactose-composed oligosaccharides.

The enzymic oxidation of snail galactans, of their first and second Smith degradation products and of some structurally related polysaccharides was studied. Lymnaea stagnalis galactan after one cycle of Smith degradation reacted best and native Helix pomatia galactan was almost inactive. Investigations on the structural requirements for oligosaccharides to bind to galactose oxidase showed that the branched tetrasaccharide, Gal-beta-1----6-[Gal-beta-1----3]-Gal-beta-1----1 L-Gro, in the terminal nonreducing position was the most complementary structure in the native galactan to associate with the enzyme. All nitrophenyl alpha-galactosides reacted better, and the ortho-form was 10-times more potent compared with this tetrasaccharide, indicative of the involvement of a hydrophobic region in binding. However, the beta-linked isomers were only equally or less reactive than galactose. The enzymic oxidation determined colorimetrically by transferring the peroxide formed to o-dianisidine ceased at a maximum typical for each substrate and independent of the reaction time. When the absolute turn-over rates for ortho- and para-nitrophenyl alpha-galactoside and for the beta-isomer were determined by HPLC, it could be demonstrated that the oxidation had not finished at the maximum of the colour reaction, but proceeded until the substrate was consumed. The initial speed of the colour reaction paralleled the absolute oxidation rate.

Animals↗

PubMed1987

Reproductive cycle, thyroxine and corticosterone in females of the giant swamp frog Dicroglossus occipitalis at the equator.

Females of the giant swamp frog Dicroglossus occipitalis were captured in the tributaries of the Zaïre River near Kisangani, a town situated close to the equator (00 degree 31' N) with virtually constant conditions as to photoperiod, temperature, precipitation, and relative humidity. An annual variation in the reproductive capacity of this species could be demonstrated. A reproductive quiescence with a low gonadal somatic index (GSI), undeveloped eggs, and minimal plasma concentrations of estradiol-17 beta (E2) and progesterone (P4) was found from October to January. E2 and P4 and thyroxine (T4) contents of the thyroids were positively correlated with GSI and egg size. Plasma T4 concentrations, however, were negatively correlated with GSI, whereas variations in corticosterone correlated only with E2. No correlation between plasma concentrations of glucose and GSI or all other hormonal parameters could be found. It is concluded that during egg maturation, increased amounts of E2 and P4 are produced. The observed variations in thyroidal and plasma T4 may be the result of an activation of thyroid function by the peripheral conversion of T4 into triiodothyronine.

Animals↗

PubMed1987

Proposal of limit concentrations for skin irritation within the context of a new EEC directive on the classification and labeling of preparations.

In this study, solvents belonging to different chemical families were tested for their irritating properties to the skin. The irritating potential of a chemical is expressed as its concentration in a nonirritant diluent beyond which irritation of the skin may be expected in the sense of EEC Directive 79/831/EEC. The substances were applied onto the shaved skin of rabbits by means of a modified Finn chamber for 4 hr. Afterward the exposure chamber was removed and the skin cleaned. Reading of erythema and edema was performed according to the scale of Draize at 1, 24, 48, and 72 hr after the removal of the patch. On the basis of the readings obtained the different dilutions of the organic solvents tested were classified as irritant or not according to the interpretation rules laid down in EEC Directive 83/467/EEC. On the basis of the structure-activity relationships found within each chemical family the irritation potential of the other members of the family could be derived via interpolation.

Alcohols↗