Biomedical subjects

J H Anderson

Publications and source records attributed to J H Anderson.

At least 145 records · Page 8Linked to original sources

PubMed1987

A reservoir model for repeated CSF access in the rabbit.

A simple, reliable and inexpensive subcutaneously implanted reservoir-catheter system method was developed for repeated sterile access to the rabbit brain ventricular system. The system provides an avenue for the repeated intrathecal administration of drugs and for the withdrawal of cerebrospinal fluid (CSF). Reservoirs were subcutaneously implanted under the scalp and connected to tubing inserted into the cisterna magna or the lateral ventricle. The systems successfully functioned in 38 of 41 animals (12 with cisternal magna catheters and 29 with lateral ventricle catheters), for up to 12 weeks following implantation. Patency of the systems were documented with X-rays and radiopaque injected contrast medium.

Animals↗

PubMed1987

Thermodynamic correlates of hot tip laser angioplasty.

Surface temperatures of normal human cadaver arteries and polytetrofluoroethylene grafts were measured in vitro using thermography to assess vascular wall heating from the metal-capped ("hot tip") laser probe. Laser pulse duration, vessel diameter, blood flow, and saline infusion were varied; power from an Argon laser was constant at 10 watts. The surface temperatures resulting in perforation were 76.2 +/- 2.2 degrees C for arteries and 90.4 +/- 2.1 degrees C for grafts. Blood flow provided an effective heat sink reducing artery and graft wall peak temperatures from 10 watt/5 sec pulses by 12.2 +/- 1.7 and 14.1 +/- 6.1 degrees C at 100 mL/min, and by 16.3 +/- 2.4 and 22.4 +/- 4.9 degrees C at 500 mL/min, respectively. In the occluded conduit, inflow of saline proximal to the probe tip reduced peak temperatures (degrees C) from 10 watt/5 sec pulses as follows: 14.0 +/- 3.2 (artery) and 23.2 +/- 8.5 (graft) at 50 mL/min, and 19.0 +/- 0.6 (artery) and 26.6 +/- 8.5 (graft) at 100 mL/min. Radial heating by the hot tip probe can cause thermal perforation. Blood flow or saline infusion modifies nontarget heating and may offer significant protection to the vasculature.

Arteriosclerosis↗

PubMed1987

Acute pancreatitis and non-Hodgkin's lymphoma.

We report two patients presenting with acute pancreatitis, the aetiology of which was subsequently proven to be non-Hodgkin's lymphoma. Histological confirmation of tumour-associated pancreatitis is essential so that appropriate therapy can be planned.

Acute Disease↗

PubMed1987

Involvement of endogenous opiates in glucose-stimulated hyperinsulinism of canine endotoxin shock. Inhibition by naloxone.

Hyperinsulinism has been associated with infection and endotoxin shock in rodents, dogs, and humans. In dogs with Escherichia coli-induced endotoxin shock, this hyperinsulinism was in response to glucose administration. To determine the role of endogenous opiates in endotoxin-induced glucose-stimulated hyperinsulinism, plasma beta-endorphin, Met-enkephalin, Leu-enkephalin, insulin, and glucose concentrations were measured for 6 h in fasted, anesthetized dogs given LD70 of E. coli endotoxin; endotoxin and glucose; endotoxin, glucose, and naloxone (an opiate antagonist); glucose and naloxone; or glucose alone. Plasma endogenous opiate immunoreactivity was elevated in dogs that received endotoxin, regardless of the presence of glucose or naloxone. The elevation of plasma Met-enkephalin and beta-endorphin preceded the onset of hyperinsulinism, but the elevation of plasma Leu-enkephalin did not. Plasma insulin was elevated 100-fold by 360 min in dogs given endotoxin and glucose. The magnitude of this hyperinsulinism was markedly reduced by naloxone, supporting the hypothesis that endogenous opiates are involved in the development of the glucose-stimulated hyperinsulinism associated with endotoxin shock. Interestingly, naloxone, given in conjunction with glucose, appeared to have a stimulatory effect on insulin secretion.

Animals↗

PubMed1987

Cochleovestibular nerve sections in labyrinthectomized patients.

Labyrinthectomy is indicated for a patient who has unilateral peripheral labyrinthine disease with unserviceable hearing loss. For most patients, labyrinthectomy provides complete relief from intractable vertigo. Some patients continue to have persistent vertigo, however, even after a complete destructive labyrinthectomy. Only after cochleovestibular nerve sections were these patients relieved of intractable vertigo. Representative cases of cochleovestibular nerve sections in labyrinthectomized patients are presented. The reason why the cochleovestibular nerve section relieves the symptom of vertigo in labyrinthectomized patients is not clear. Labyrinthectomy destroys vestibular sense organs, while cochleovestibular nerve section eliminates spontaneous activity and prevents the possibility of nerve regeneration by excision of the ganglion. For those patients who required vestibular nerve sections, there may have been abnormal excitation of vestibular nerve fibers. This might be explained by incomplete labyrinthectomy, regeneration of vestibular nerve fibers, contribution from vestibular ganglia or nonfunctioning cochlea, and vascular loop syndrome.

Aged↗

PubMed1986

Blood flow to experimental renal tumors.

Radiolabeled microsphere techniques were used to measure renal blood flow (RBF) in rabbit kidneys with 14- to 16-day-old experimentally induced renal tumors. VX-2 carcinoma cells (25 microliters) harvested from carrier animal intramuscular tumors were injected supraselectively into an intralobar artery using fluoroscopically guided transcatheter techniques. Within 2 to 3 weeks, all animals developed localized 10 to 25 mm diameter renal tumors. Renal blood flow was calculated after left ventricular injection of 113Sn-labeled 15 mu diameter microspheres. Blood flow (ml/minute) in tumor-bearing kidneys (26.91 +/- 1.86) was significantly lower (P = less than .05) than in normal controls (49.79 +/- 7.71). The tumor-bearing kidneys were also significantly larger (15.21 +/- 1.27 gm) than control animal kidneys (10.89 +/- 0.071 gm). Analysis of the tumor kidneys showed flow (ml/minute/g) in the tumor-containing sections (1.82 +/- 0.15) and in the actual tumor tissue (0.62 +/- 0.07) to be significantly lower (P = less than .05) than (1) in the nontumor portions of the same kidneys (2.58 +/- 0.28), and (2) in the tumor animals' contralateral nontumor-bearing kidneys (3.22 +/- 0.16), and (3) in normal control animal kidneys (4.54 +/- 0.29). The reduced flow in tumor-bearing kidneys was not an artifact due to arteriovenous shunting, as demonstrated by 99mTc-microsphere studies in four additional tumor-bearing animals. This study has shown that blood flow to the tumor is extremely low compared with nontumor-containing ipsilateral, contralateral, and normal control renal tissue. These results provide important information relative to possible experimental therapeutic research involving embolization or pharmacologic manipulation of the blood supply to potentiate intra-arterial chemotherapy.

Animals↗

PubMed1986

Measurement of peripheral blood flow by thermodilution techniques.

Recent advances in the diagnosis and treatment of cardiovascular pathology, including balloon angioplasty of atherosclerotic lesions in peripheral vascular disease, have led to an increased need for in vivo quantitation of blood flow. This study has three purposes: (1) to validate thermodilution techniques as a viable method for measuring low blood flow rates, (2) to calibrate accurately thermodilution catheters at these low flows, and (3) to develop an animal model that can be used to quantitate and compare many different flow measuring techniques. Modified commercially available 6F thermodilution catheters were used with a standard cardiac output computer to measure flows between 200 and 700 ml/minute. Eight anesthetized dogs were surgically interfaced with a variable flow, pressure, and compliance carotid-carotid/jugular bypass perfusion system. Three milliliters of normal saline at room temperature were injected through the catheters intra-arterially to measure different flows below, at, and above physiologic pressures and compliances. Results of this study indicate that with proper calibration, thermodilution techniques of measuring arterial and venous flows between 200 and 700 ml/minute are simple, accurate, and reliable. Using the designed system to generate known flows in vivo at various physiologic conditions allowed easy calibration of catheters and should facilitate calibration and comparison of other measurement techniques.

Animals↗

PubMed1986

Percutaneous spermatic vein occlusion: evaluation of sclerosing agents in experimental animals.

The 5%-20% rate of recurrence of testicular varicoceles after embolotherapy has been a persistent clinical problem. Three sclerosing agents--sodium tetradecyl sulfate 3%, absolute ethanol, and 100 degrees C contrast material--were evaluated in canine spermatic veins for degree and durability of venous occlusion. Pathologic examination for perivenous, pulmonary, and neural changes was performed. Both sodium tetradecyl sulfate and absolute ethanol were effective sclerosants, but sodium tetradecyl sulfate was technically easier to use. The use of a sclerosant in conjunction with balloons or coils is the safest, most effective technique for occluding variococeles and minimizing postembolotherapy recurrences.

Animals↗

PubMed1986

Maternal-fetal distribution of morphine and alfentanil in near-term sheep and rhesus monkeys.

Maternal-fetal distribution of the opiate agents morphine and alfentanil was studied in 3 near-term sheep and rhesus monkeys. Blood samples were obtained from maternal and fetal arteries for radioimmunoassay after placement of catheters under halothane anesthesia. Fetal-maternal ratios (F/M) of plasma morphine concentrations for sheep increased from 0.04 to 0.47 during the first hour after bolus IV injection of 200 micrograms/kg morphine. However, in monkeys, F/M values were considerably higher, increasing from 0.27 to 1.85. Indeed, values over 1.00, indicating higher drug concentrations in fetal than maternal plasma, were seen in two monkeys at 10 and 60 min time points. For alfentanil, a more lipid soluble but highly protein-bound drug, F/M values of plasma concentrations were similar in the two species ranging from 0.1 to 0.6 after injection of 250 micrograms/kg in sheep and 125 micrograms/kg in monkeys. Quantitation of morphine glucuronide, the principal metabolite of morphine and total morphine-like immunoactivity, suggested that morphine was metabolized more rapidly in monkey dams than in sheep, and that morphine glucuronide was more readily distributed to monkey than sheep fetus. These data suggest that morphine, but not alfentanil, transfers more readily from dam to fetus in near-term monkeys than in sheep.

Alfentanil↗

PubMed1986

Carotid bifurcation imaging model for more accurately comparing imaging techniques.

For comparing current and presubably forthcoming imaging modalities, a carotid bifurcation model was made from cadaveric specimens. Perfusing and pulsing the immersed common carotid artery and its proximal branches via a Harvard pump simulated clinical imaging conditions. Film-screen (F-S) and digital subtraction (DS) angiography, computed tomography (CT), ultrasound and magnetic resonance imaging (MRI) were compared. For CT and MRI, scanning parameters such as slice thickness, degree of overlapping, amount of contrast medium needed, scanning mode and multiplanar and three-dimensional techniques enabled enhancing the capacity for CT in the clinical setting. Direct axial CT proved to be most accurate for assessing the contours and magnitude of carotid narrowing. Nonetheless, these serial segments were not readily compared with F-S and DS angiographic full length images. The use of multiplanar reconstruction (MPR) and three-dimensional (3-D) CT achieved this and furthermore showed the external contour of the diseased segment. Concerning carotid ulceration, our carotid model study showed CT to be equally accurate with DS and superior to F-S angiography. However, in our clinical study of 34 carotid arteries in 17 patients ulcerations were equally well identified by CT and angiography but DS angiography proved superior in identifying ulcers not seen with CT. Perhaps this discrepancy is explained by the clinical routine of attaining multiple fluoroscopically positioned views of the common carotid bifurcations in DS catheter angiography unlike the complexity of attaining optimal views of tortuous vessels on CT.

Angiography↗

PubMed1986

Adaptation of pregnant rhesus monkeys to short-term chair restraint.

Heart rate, blood pressure, temperature and plasma corticosteroids were measured in pregnant rhesus monkeys during 23 successive 2 hour chair restraint periods beginning in midgestation. Heart rate (15%), blood pressure (13%) and plasma cortisol (23%) declined from first to last sessions. Reduction in physiological indicators of stress was most marked during the first three sessions, but continued in some animals over the 8 week period. Pulse rate and blood pressure were elevated at the beginning of each session and dropped to base-line levels during the second hour. In contrast, plasma cortisol consistently rose during the 2 hour session. Blood sampling and palpation were conducted at weekly intervals during the adaptation series. Immediate physiological responses to these manipulations did not diminish with repetition, although behavioral adaptation was observed. The data suggests that objective measurements of adaptation to chair restraint are important in determining the appropriateness of this procedure. Chair restraint is a valuable alternative to chemical or manual restraint in obtaining sequential evaluations in pregnant monkeys.

Adaptation, Physiological↗

PubMed1985

Gestational age and the management of preterm labor in obstetric programs.

The gestational age at which obstetric training programs aggressively manage and attempt to salvage preterm vertex fetuses in distress was determined by survey. More than half the programs initiate fetal monitoring and perform cesarean section for certain cases of fetal distress by 26 weeks gestational age. By 28 weeks gestational age, most programs consistently perform a cesarean delivery for a vertex fetus in distress. Management practices in university training programs appear to be more aggressive than those in nonuniversity programs. Not all programs--either within or outside the university--try aggressively to salvage fetuses in distress at 28 weeks gestational age or more, however, despite the excellent chance for survival and normal development.

Cesarean Section↗

PubMed1985

Role of prostaglandins in control of intestinal motility.

Intestinal myoelectric activity was measured in four conscious dogs with implanted monopolar electrodes after administration of prostaglandins (PG) and indomethacin (Indo), a potent inhibitor of PG biosynthesis. PGE2 and PGI2 given intravenously caused a dose-dependent decrease in the frequency of the migrating myoelectric complex (MMC) in fasted dogs and in postprandial spike activity in fed animals. In contrast, PGF2 alpha interrupted the MMC and caused a fedlike pattern in fasted dogs and did not affect the postprandial spike activity. Similar effects were observed after intra-arterial infusion of PGs. PGE2 and PGI2 infused into the superior mesenteric artery caused a dose-dependent inhibition of the fasted and postprandial pattern of myoelectric activity of the small bowel, whereas PGF2 alpha blocked the MMC and increased spike activity. Indo injected in a single intravenous dose caused a significant reduction in the MMC interval, and Indo infused intravenously in a constant dose induced fedlike motility pattern in fasted dogs but had little effect on the postprandial activity in these animals. This study demonstrates that exogenous PGs of E and I series administered intravenously or intra-arterially inhibit intestinal motility, whereas PGF2 alpha has opposite effects. The finding that Indo increases intestinal motility indicates that endogenous PGs are important in the physiological control of intestinal motility.

Animals↗

PubMed1985

Asymmetry of vestibulo-ocular reflex in the cat.

Vertical eye movements were recorded in alert, restrained cats that were subjected to whole-body rotations which stimulated the vertical semicircular canals. The results showed a significant asymmetry between the upward and downward slow-phase eye movements, which suggests differences in the CNS processing of vertical canal inputs vis-á-vis the vestibulo-ocular reflex.

Animals↗

PubMed1985

Allergenic airborne pollen and spores in Anchorage, Alaska.

Major aeroallergens in Anchorage are birch, alder, poplar, spruce, grass pollen, Cladosporium, and unspecified fungus spores. Lesser pollens are sorrel, willow, pine, juniper, sedge, lamb's-quarters, wormwood, plantain, and others. The aero-flora is discussed in terms of the frequency of allergenically significant events and within-season and year-to-year dynamics.

Air Pollution↗

PubMed1984

Correction of congenital hydrocephalus in utero II: Efficacy of in utero shunting.

To study the effect of in utero ventricular decompression of hydrocephalus on brain development and prognosis, and to evaluate the function and possible complications of different shunt designs, we created fetal hydrocephalus in 28 fetal lambs and 17 fetal monkeys by injecting kaolin into the cisterna magna during the third trimester. One fetal lamb had indwelling intracranial subdural and amniotic cavity pressure catheters placed to study serial changes in the relationship of intracranial pressure (ICP) and amniotic fluid pressure (AFP) from the time of injection until term. Twenty hydrocephalic fetal lambs underwent ventricular decompression--ventriculoamniotic (V-A), N = 10; ventriculo-right atrial (V-RA), N = 9; and ventriculo-pleural (V-PL), N = 1--21 to 25 days after the kaolin was injected; seven hydrocephalic fetuses were left unshunted as controls (CON). Eight fetal monkeys underwent V-A decompression 14 to 21 days after kaolin injection; nine were left unshunted as controls. All animals were delivered by cesarean section near term, assessed for viability and their brains examined grossly and microscopically. After kaolin injection in the fetal lamb, ICP (r = 0.94) and ICP minus AFP (r = 0.93) rose in a linear fashion, while AFP showed no trend (r = 0.22). All unshunted newborn lambs and monkeys had split sutures, dilated ventricles, and thinned cortical mantle. Most shunted lambs showed anatomic improvement with decreased head circumference, overriding sutures, normal-sized ventricles, and improved survival. However, histopathology revealed marked white matter destruction. In contrast, most shunted monkeys showed little anatomic improvement. Both shunted and unshunted monkey brains showed a severe inflammatory ventriculitis. In both lambs and monkeys, shunting was associated with a variety of complications including subdural hematoma, subdural hygroma, shunt infection, shunt occlusion, and improper shunt tip placement. In this experimental model, in utero decompression of obstructive hydrocephalus improves overall survival, improves gross ventriculomegaly, does not improve histopathologic brain damage, and is associated with significant complications. The choice of the optimal shunt design and the effect on postnatal neurologic function requires further study. This work emphasizes the need for continuing research in an animal model prior to human application.

Amniotic Fluid↗

PubMed1984

Percutaneous transluminal balloon valvuloplasty for pulmonary valve stenosis.

Transluminal balloon valvuloplasty was used to treat congenital pulmonary valve stenosis in 20 patients. Follow-up cardiac catheterization was performed in 11 patients at intervals of from 2 to 12 months after the procedure. Peak systolic pressure gradient across the pulmonic valve decreased from 68 +/- 27 to 23 +/- 5 mm Hg (p less than .001) after valvuloplasty. There were no complications. Follow-up catheterization demonstrated persistent relief of right ventricular hypertension in the patients with typical pulmonary valve stenosis.

Adolescent↗

PubMed1984

Diarrhea in nonhuman primates: a survey of primate colonies for incidence rates and clinical opinion.

Veterinary clinicians associated with 18 colonies of nonhuman primates were surveyed for their experience with diarrhea disease in colony animals for calendar year 1981. The 1981 diarrhea incidence rate, diarrhea-specific mortality rate and diarrhea case fatality rate for 13,385 monkeys were 10.6%, 1.2% and 11.1%, respectively. It was not possible to incriminate age or type of housing as risk factors for diarrhea, but some species seemed at greater risk than others. Erythrocebus patas monkeys had relatively high diarrhea incidence rates (18.8%) and the highest case fatality rate (48.4%) of all species surveyed. Squirrel monkeys (Saimiri sciureus) and baboons (Papio sp.) had low diarrhea incidence rates (2.1% and 3.2%, respectively). This opinion survey indicated a lack of uniformity among primate clinicians with respect to approaches to diagnosis and therapy of monkey diarrhea. The survey also suggested that many of the agents associated were perceived differently among primate clinicians, and that the roles of some agents are still poorly understood.

Age Factors↗