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Biomedical subjects

G Jacobs

Publications and source records attributed to G Jacobs.

At least 19 recordsLinked to original sources
PubMed1992

Sarcoidosis associated with nephrocalcinosis in young children.

Three patients with nonpulmonary sarcoidosis had chronic erythema nodosum within the first 2 years of life. Each subsequently had renal sarcoidosis and nephrocalcinosis; hypercalcemia was documented in each patient and hypercalciuria in two patients. Treatment with prednisone was not uniformly successful in normalizing creatinine clearance. Nephrocalcinosis may be more common than previously reported in patients with sarcoidosis.

Biopsy↗
PubMed1992

Selective stimulation of parasympathetic nerve fibers to the human sinoatrial node.

BACKGROUND: In animals, parasympathetic nerve fibers that innervate the sinoatrial node can be selectively stimulated to increase atrial cycle length. These nerve fibers course through an epicardial fat pad at the margin of the right superior pulmonary vein, the superior vena cava, and the right atrium. We hypothesized that similar nerves exist and can be selectively stimulated in humans. METHODS AND RESULTS: Microscopic examination of fat pads excised from the margin of the right superior pulmonary vein, the superior vena cava, and the right atrium during two human autopsies revealed the presence of nerve fibers and ganglia. We electrically stimulated this epicardial fat pad in 16 patients during cardiac surgery. The fat pads were stimulated with continuous-pulse trains for 15 seconds via a hand-held bipolar electrode using constant current (10-15 mA), constant pulse width (0.02-0.05 msec), and at 6.6, 10, 20, 25, and 30 Hz. The mean atrial cycle length +/- 1 SEM increased from 734 +/- 34 msec at baseline to a maximum of 823 +/- 61 msec at 6.6 Hz, 1,167 +/- 125 msec at 10 Hz, 1,734 +/- 281 msec at 20 Hz, 2,993 +/- 661 msec at 25 Hz, and 2,461 +/- 668 msec at 30 Hz during nerve stimulation. Linear regression analysis showed that the response of atrial cycle length to sinoatrial parasympathetic nerve stimulation was frequency dependent. The maximum response and complete decay of the response occurred within 4-8 seconds of initiation or termination of sinoatrial parasympathetic nerve stimulation. Atrioventricular conduction time and the PR interval did not change during sinoatrial parasympathetic nerve stimulation, even when the atria were paced at the baseline heart rate. CONCLUSIONS: Electrical stimulation of parasympathetic nerve fibers in a fat pad near the sinoatrial node increased atrial cycle length without affecting atrioventricular nodal conduction. This is the first study in which such nerve fibers that innervate the sinoatrial node have been selectively stimulated in humans.

Adipose Tissue↗
PubMed1991

The galactan-degrading enzymes in the snail Biomphalaria glabrata.

1. Embryonic snails incorporate from the perivitelline fluid in which they are embedded a polysaccharide, called galactan, which is composed entirely of D-, or D- and L-galactose. In this investigation the p-nitrophenyl-beta-D-galactoside degrading enzyme of Biomphalaria glabrata which was assumed to be involved in the degradation of the galactans was purified almost to homogeneity and its specificity was studied. 2. It has a mol. wt of 135,000 and is composed of two identical subunits. 3. It could be shown that p-nitrophenyl-beta-D-fucoside was hydrolysed eight times faster, but native galactan was neither decomposed nor was it inhibitory for the hydrolysis of p-nitrophenyl-glycosides. 4. Thus, it is most likely that this galactosidase is not involved in the galactan metabolism. 5. However, a membrane-bound enzyme complex was revealed which was able to metabolize the native galactan of Biomphalaria glabrata completely and which showed graded reactivity towards galactans of other species. 6. Since no intermediate degradation products were found it must be assumed that they were metabolized further in the mitochondria.

Animals↗
PubMed1990

Electrical control of gastric emptying in denervated and reinnervated canine stomach: a pilot study.

Gastric emptying of solids is abnormally slow after vagotomy. To determine whether it was possible to accelerate emptying by electrical stimulation either of the gastric wall directly or of a "foreign" nerve brought in to reinnervate the stomach, eight dogs underwent truncal vagotomy (TV); five of the dogs received intercostal nerve muscle pedicle (NMP) implants. Gastric atony was demonstrated postoperatively in all animals up to 4 months later by means of radiological contrast studies. After allowing time for neurotization to occur (mean 78 days), the cervical vagi were stimulated to confirm that TV was complete. Gastric peristalsis, intraluminal pressures, and emptying were assessed during stimulation of the NMPs and of the gastric wall, followed by sacrifice for histologic study. Neither reinnervation alone nor stimulation of the NMPs improved emptying. Although viable somatic nerve was found in the gastric wall, nerve sprouting was not. By contrast, stimulation of the gastric wall with trains of pulses (20 Hz, 2-10 ms, 2-5 mA) evoked peristalsis in all animals. We conclude that somatic nerve tissue cannot produce functional reinnervation of a visceral organ; however, direct muscular stimulation can accelerate gastric emptying after TV.

Abdominal Muscles↗
PubMed1990

Infectious crystalline keratopathy associated with topical anesthetic abuse.

Two patients with infectious crystalline keratopathy associated with topical anesthetic abuse are described. No previously reported predisposing factors existed, including topical corticosteroid use during active Herpes simplex or Acanthamoeba keratitis, or following penetrating keratoplasty. Cultures from corneal biopsies of both patients grew Streptococcus viridans. Both infections resulted in corneal scarring with vascularization. Ultimately, corneal transplantation was performed in one case.

Adult↗
PubMed1990

Plasma, tissue, and urine carnitine concentrations in healthy adult cats and kittens.

Mean carnitine concentrations [( carnitine]) were higher (P less than 0.05) in adult cats than in kittens for skeletal muscle (total and free carnitine), myocardium (free carnitine), and urine (total and free carnitine). The free/total carnitine ratio was lower (P less than 0.05) in kittens than in adults for liver, myocardium, and urine. Carnitine concentrations were similar between genders in kittens, but in adult cats, [carnitine] in plasma (total, free, and esterified carnitine) and liver (total and free carnitine) were higher (P less than 0.05) in female than in male cats. Total and free plasma [carnitine] were correlated to total and free liver [carnitine], respectively. Skeletal muscle [carnitine] was not correlated to plasma [carnitine]. Correlations in [carnitine] between plasma and myocardium, kidney, or urine were inconsistent.

Animals↗
PubMed1990

Comparison of plasma, liver, and skeletal muscle carnitine concentrations in cats with idiopathic hepatic lipidosis and in healthy cats.

Concentrations of total, free, and esterified carnitine were determined in plasma, liver, and skeletal muscle from cats with idiopathic hepatic lipidosis and compared with values from healthy cats. The mean concentrations of plasma, liver, and skeletal muscle total carnitine; plasma and skeletal muscle free carnitine; and plasma and liver esterified carnitine were greater (P less than 0.05) in cats with idiopathic hepatic lipidosis than in control cats. The mean for the ratio of free/total carnitine in plasma and liver was lower (P less than 0.05) in cats with idiopathic hepatic lipidosis than in control cats. These data suggest that carnitine deficiency does not contribute to the pathogenesis of feline idiopathic hepatic lipidosis.

Animals↗
PubMed1989

Treatment of idiopathic hepatic lipidosis in cats: 11 cases (1986-1987).

Idiopathic hepatic lipidosis was diagnosed in 11 cats. Cats were treated by delivery of balanced nutrients supplemented with L-carnitine via a surgically placed gastrostomy tube. Feeding through the gastrostomy tube was initiated in the hospital and was continued at home in all cats. The mean duration of gastrostomy tube feeding was 48 days (range, 22 to 98 days). Vomiting associated with feeding (3 cats) and localized cellulitis at the gastrostomy site (2 cats) were the most frequent complications. Vomiting was controlled by reducing the volume of food administered at each feeding or by administration of metoclopramide. Cellulitis was treated successfully by parenteral administration of antibiotics and local wound cleansing. Seven of 11 cats (65%) survived and have remained clinically healthy for 15 to 29 months (mean, 20 months) since diagnosis. The other 4 cats died of peritonitis (n = 1), pneumonia (n = 1), hepatic encephalopathy (n = 1), or cardiopulmonary arrest (n = 1) between 0 and 10 days after surgery.

Animals↗
PubMed1989

[Electrostimulation of ileum and jejunum reservoirs in an acute and chronic experiment].

Voluntary control of the motility of intestinal reservoirs may be used to improve evacuation and continence. In 4 dogs a U-shaped jejunum pouch and in another 4 an ileum pouch was constructed and instrumented with stimulating and EMG electrodes and pressure lines. In the acute experiments jejunum pouch stimulation with 200 microseconds 1.67 kHz 30 mA increased the intrapouch pressure by 38 +/- 4 mm Hg (n = 6) and 500 microseconds 910 Hz 25 mA by 60 +/- 5 mm Hg (n = 3). The pressure increase in the awake animals was consistently lower (200 microseconds 4 +/- 6 mm Hg, n = 9; 500 microseconds 25 +/- 17, n = 11). The ileum pouch responded with a 37 +/- 10 mm Hg pressure increase (n = 9) to 50 ms 6 Hz 20 mA pulse trains. Ileum pouches could not be stimulated in the awake animal due to contraction of the abdominal wall. Electrostimulation may be used to contract and evacuate intestinal reservoirs but additional drug therapy or autonomic nerve stimulation will be necessary to lower the thresholds especially for ileum stimulation in the awake animal.

Animals↗
PubMed1989

Transient blueberry muffin appearance of a newborn with congenital monoblastic leukemia.

A full-term male infant was born with skin findings suggesting a blueberry muffin appearance. Biopsy of a cutaneous nodule was consistent with monoblastic leukemia cutis, and bone marrow examination confirmed the diagnosis of leukemia. The infant has remained well 2 years after spontaneous resolution of the cutaneous eruption. Infiltrative neoplasms should be considered along with congenital infections and hematologic disorders in the differential diagnosis of a newborn with a blueberry muffin appearance.

Biopsy↗
PubMed1989

Contractile response to electrical stimulation of the small intestine in anesthetized and awake dogs.

To test whether small bowel contraction can be induced by electrostimulation similar to in vitro results in anesthetized and awake animals, five dogs had stainless steel electrodes implanted on the serosal surface of the jejunum and ileum. Fifty milliamperes of 500-microseconds 910-Hz currents induced a 50-80-mm Hg pressure increase in the jejunum with a threshold of 25 mA. Transverse stimulation was studied long-term in two dogs. The mean pressure change for 500-microseconds 910-Hz 25-mA stimulation in 10 studies was 26 mm Hg (0-75). The thresholds ranged between 15 mA and currents not tolerated by the animal. For 200-microseconds 1.67-kHz 30-mA stimulation, the mean pressure change was 28 mm Hg (0-75 mm Hg, n = 16). On 10 occasions, the pressure increased further after termination of the stimulus (off response), with a mean of 48 mm Hg (10-85). Electrical currents elicit a mechanical response in the small intestine of the intact animal, which resembles the in vitro observations. Currents necessary to evoke contractions in the physiologic range are tolerated by the trained animal.

Anesthesia, General↗
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↗