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Biomedical subjects

R L Anderson

Publications and source records attributed to R L Anderson.

At least 163 records · Page 9Linked to original sources
PubMed1991

Association of vascular compression in trigeminal neuralgia versus other "facial pain syndromes" by magnetic resonance imaging.

Magnetic resonance imaging was performed in 13 patients with trigeminal neuralgia and 18 control patients with facial pain of other types. Among trigeminal neuralgia patients, eight (62%) had vessels seen abutting, or immediately adjacent to, the trigeminal nerve on the side of their symptoms. Only three control patients (17%) had such vessels. The proportion of patients having a trigeminal region vessel associated with their symptoms was significantly higher in patients with trigeminal neuralgia than in controls (p = 0.0086). These findings provide evidence supporting the theory that trigeminal neuralgia is associated with vascular compression of the fifth cranial nerve.

Constriction, Pathologic↗
PubMed1991

Effects of oral administration of a high-molecular-weight crosslinked polyacrylate in rats.

Oral feeding studies of a crosslinked, high-molecular-weight polyacrylate polymer (PA) were conducted to (1) characterize the biological effects following exposure to either 0, 300, 1000, or 3000 mg PA/kg/day for 93 days; (2) characterize the fecal and urinary mineral excretion at these same dose levels; and (3) monitor the absorption, distribution, and excretion (ADE) of radiolabeled PA following a single oral exposure. The subchronic study results indicate that dietary intake of up to 3000 mg/kg/day PA had no adverse histopathology, hematology, body weight, or clinical chemistry effects in rats. Dietary exposure to PA did, however, result in an elevation in urinary excretion of sodium and phosphorus, whereas excretion of magnesium, calcium, and potassium was lowered. A more detailed study demonstrated that although the urinary excretion of these minerals was changed, total recovery of the minerals (feces + urine), except for sodium, was not different from that for controls. An increase in sodium excretion was expected since PA was in the form of a sodium salt. The ADE studies following a single oral dose of PA indicate that the majority of dosed PA (91.9%) was excreted in the feces. As expected, a small percentage (approximately 3.5%) was absorbed, possibly metabolized, and excreted. In summary, the oral administration of high levels of PA resulted in (1) no histological, hematological, or clinical chemistry changes; (2) no alteration in the overall mineral excretion (feces + urine) with the exception of sodium; and (3) primarily fecal excretion of orally administered PA.

Acrylic Resins↗
PubMed1991

Heterogeneity of heat response in murine, canine and human tumors: influence on predictive assays.

The heterogeneity of response to hyperthermia of cells taken from different regions of tumors was tested in a model tumor system (RIF-1) in the mouse and in specimens from spontaneous tumors taken from dogs and humans at the time of surgical resection. Cell survival was assayed by clonogenic survival in the murine tumor and by dansyl lysine staining in tumors from all three species. Using survival as an endpoint, it was found that the extent of heterogeneity depended on the temperature to which the tumor was heated and the duration of exposure. By increasing either of these factors, the coefficient of variation was increased. The large heterogeneity seen after in vivo heating could not be explained entirely by inhomogeneous heating within the tumor as evidenced by temperature mapping. It is concluded that other microenvironmental factors such as blood flow, pH, O2, and nutrient supply may cause variations in the heat response of the tumor cells in vivo. Little, if any, evidence of cellular heterogeneity was evident for all three species when comparisons were made between samples of 100-200 mg. The canine and human tumors were considerably more heat resistant when dansyl lysine was used as an endpoint. In the RIF-1 tumors, heterogeneity of heat response was greater after in vitro heating than after in vivo heating when small biopsy samples (10-20 mg) were taken, suggesting that some cellular heterogeneity was present.

Animals↗
PubMed1991

Investigations of intrinsic Pseudomonas cepacia contamination in commercially manufactured povidone-iodine.

OBJECTIVE: Laboratory investigations were initiated with a povidone-iodine antiseptic solution that was intrinsically contaminated with Pseudomonas cepacia. These investigations were helpful in understanding the microbicidal and chemical properties of iodophor solutions and the mechanism by which P cepacia can survive in iodine-containing antiseptics. DESIGN: Included in these studies were: prolonged survival of P cepacia; available and free iodine determinations; microbial challenge studies; and scanning electron microscopic examination of contaminated antiseptic. RESULTS: P cepacia survived in this iodophor antiseptic up to 68 weeks from the date of manufacture. A uniform concentration of 1% available iodine was found in all lots of povidone-iodine tested as specified on the product label, but free iodine (I2) values varied greatly. Low free iodine levels of 0.23 to 0.46 ppm were associated with the contaminated lot of povidone-iodine. Solutions of povidone-iodine with varying levels of free iodine were rapidly microbicidal when challenged with cells of P cepacia derived from culture broth and washed or adapted to growth in water. P cepacia cells taken directly from contaminated povidone-iodine survived for significantly longer periods of time. Large numbers of P cepacia were found embedded in extracellular material and among strands of glycocalyx between cells as shown by scanning electron microscopy. CONCLUSIONS: The physical thickness of cellular and extracellular material that forms on surfaces could protect embedded organisms from the microbicidal action of disinfectants and antiseptics and subsequently allow for extended microbial survival times. Manufacturers should be aware that distribution piping surfaces colonized with bacteria may be a source of product contamination and resistant organisms.

Colony Count, Microbial↗
PubMed1991

Botulinum-induced alteration of nerve-muscle interactions in the human orbicularis oculi following treatment for blepharospasm.

To assess longstanding alterations in human muscle innervation induced by botulinum toxin, we studied motor axons in the orbicularis oculi of nine patients previously injected with botulinum toxin for treatment of benign essential blepharospasm (BEB). Compared with untreated BEB and normal orbicularis oculi, muscle exposed to botulinum toxin developed persistent and cumulative alterations of innervation, including (1) thin, unmyelinated axonal collaterals that contact muscle end plates, (2) an increased number of muscle fibers innervated by individual terminal motor axons, (3) a profusion of unmyelinated axonal sprouts that end blindly, (4) an increased range of end plate sizes, and (5) multiple end plates on individual muscle fibers. The findings suggest that axonal sprouts which develop after botulinum-toxin-induced functional denervation can form new end plates. A single muscle fiber may then be innervated at separate sites by more than one axon.

Adult↗
PubMed1991

Facial dystonia, essential blepharospasm and hemifacial spasm.

Movement disorders, or dyskinesias, in the facial region may be categorized in several ways. Dystonic movement disorders in the cranial-cervical region, including essential blepharospasm, Meige syndrome and spasmodic torticollis, are characterized by uncontrollable squeezing movements in the face and neck. These disorders typically present in the fifth and sixth decades of life. Essential blepharospasm is particularly debilitating, as the involuntary eyelid closure that accompanies this condition may result in functional blindness with an otherwise normal visual pathway. Hemifacial spasm is an intermittent, unilateral, spasmodic contraction of the muscles innervated by the facial nerve. This disorder usually presents in the third or fourth decade and has a different underlying pathophysiology than the dystonias. Botulinum A toxin therapy has largely supplanted surgical intervention in the treatment of essential blepharospasm and hemifacial spasm.

Blepharospasm↗
PubMed1990

Carbohydrate-binding protein 35. Isoelectric points of the polypeptide and a phosphorylated derivative.

Purified carbohydrate-binding protein 35 (CBP35) and extracts of mouse cells containing CBP35 were analyzed by two-dimensional gel electrophoresis. Such an analysis on recombinant CBP35, obtained by expression of a cDNA clone in Escherichia coli, yielded a pI value of 8.7. When extracts of mouse 3T3 cells were subjected to two-dimensional gel electrophoresis and immunoblotting, two spots were observed, corresponding to pI values of 8.7 and 8.2. The pI 8.2 species represents post-translational modification of the CBP35 polypeptide (pI 8.7) by the addition of a single phosphate group. This conclusion is based on the finding that purified CBP35 contained a pI 8.2 species that was labeled with 32PO4 and could be converted to the unlabeled pI 8.7 species by alkaline phosphatase treatment. The phosphorylated (pI 8.2) form of CBP35 is found in both the cytosolic and nuclear fractions, whereas the unphosphorylated (pI 8.7) species is found exclusively in the nuclei. Quiescent populations of 3T3 fibroblasts (confluent monolayers or serum-starved sparse cultures) are characterized by the predominance of phosphorylated CBP35. Stimulation of the same cells into the proliferative state resulted in an increase in the amount of the phosphorylated species; more dramatic, however, is the elevation of the level of the unphosphorylated form, which is barely detectable in quiescent cells.

Animals↗
PubMed1990

Two-year carcinogenicity study of sodium fluoride in rats.

To determine the carcinogenic potential of sodium fluoride (NaF), we fed Sprague-Dawley rats a diet containing NaF for up to 99 weeks. Rats receiving NaF at a dose of 4, 10, or 25 mg/kg per day added to a low-fluoride diet were compared with controls receiving either a low-fluoride diet or laboratory chow. Each treatment group consisted of 70 rats of each sex. A 30% decrement in weight gain occurred at an NaF dose of 25 mg/kg per day. Evidence of fluoride toxicity was seen in the teeth, bones, and stomach, and the incidence and severity of these changes were related to the dose of NaF and the duration of exposure. Despite clear evidence of toxicity, NaF did not alter the incidence of preneoplastic and neoplastic lesions at any site in rats of either sex. Results from this study indicate that NaF is not carcinogenic in Sprague-Dawley rats.

Animals↗
PubMed1990

Changes in the expression of idiotype antigen on murine B-cell lymphoma after hyperthermia alone and in combination with interferon and tumour necrosis factor.

The effect of interferon (IFN) and tumour necrosis factor (TNF), either alone or combined with hyperthermia, on cell proliferation and expression of idiotype antigen on a murine B-cell lymphoma has been studied. Incubation with same doses of IFN-alpha and IFN-gamma reduced cell proliferation to the same extent. Hyperthermia potentiated the antiproliferative activity of IFN-alpha and IFN-gamma. Pretreatment with IFN-gamma induced a synergistic response with heat, while IFN-alpha and heat had an additive effect. Tumour necrosis factor (TNF) alone did not affect cell proliferation, nor did TNF modify the heat-induced delay in cell growth. The quantitative expression of surface idiotype antigen was studied by flow cytometry using an anti-idiotype monoclonal antibody (MAb). Heat reduced the expression of idiotype antigen approximately 50%. The duration of the reduction depended on the heat-dose. Recovery of antigen expression correlated with recovery of cell growth, and 2-5 days after the treatment antigen expression returned to the normal level for untreated cells. IFN-gamma and TNF increased antigen expression (30-50%) which lasted for 4-6 days after treatment. When cells were incubated with IFN-gamma or TNF for 2 days prior to hyperthermia, the increase in antigen expression was observed immediately after heating, but by the following day, antigen expression was similar to that after heat treatment alone. Expression of idiotype antigen recovered within 2-5 days to the same values as after heat treatment alone. IFN-alpha alone or combined with hyperthermia did not have any significant effect on antigen expression.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1990

The medial tarsal strip.

Medial canthal malpositions and marked medial ectropion due to laxity, scarring, or trauma can be difficult to correct. Medial canthal tendon publications have been advocated but they do not achieve adequate posterior and medial placement of the medial canthal angle and they lack permanence. One of us (R.L.A.) has developed a surgical technique for correcting these problems that is a modification of the lateral tarsal strip procedure used to correct lateral canthal tendon laxity and malposition. The medial tarsal strip procedure repositions and tightens the medial lower or upper eyelid, establishing a normal anatomic appearance. Its use is indicated in cases of medial canthal malposition or marked medial ectropion associated with a nonfunctioning canalicular system or in those cases in which loss of function of a patent canaliculus is acceptable or desirable. The advantages of the medial tarsal strip are as follows: (1) surgery is directed at the site of the defect; (2) recurrence of canthal tendon laxity and elongation is avoided; (3) a more medial and posterior positioning of the medial eyelid can be obtained; (4) any amount of eyelid laxity can be corrected simultaneously; (5) the almond-shaped canthal angle is preserved or reestablished; and (6) the procedure is fast and easily performed.

Adult↗
PubMed1990

Granulomatous acne rosacea of the eyelids.

We describe the clinicopathologic features of the papular form of granulomatous acne rosacea of the eyelids. This unusual cutaneous disorder is typified by painless eruptions of reddish to yellowish brown, occasionally ulcerative papules symmetrically distributed around the eyelids, lower part of the forehead, nasolabial folds, and upper lip. Histopathologically, the lesions display caseating and noncaseating dermal granulomas that mimic those seen in tuberculosis, tuberculoid leprosy, sarcoidosis, and other diseases. The disorder responds well to systemic tetracycline therapy but may involute spontaneously during a period of months to years. The distinction of this disorder from other dermal granulomatous diseases, such as tuberculosis, leprosy, syphilis, and foreign bodies, is important because of the different therapeutic implications.

Aged↗
PubMed1990

Whitnall's sling for poor function ptosis.

Severe unilateral ptosis with poor levator function has previously been treated with maximal levator muscle resection or bilateral or unilateral frontalis suspension. One of us (R.L.A.) has developed a technique called "Whitnall's sling," where only the levator aponeurosis is resected, preserving Whitnall's ligament and its attachments. Whitnall's ligament and the underlying resected levator muscle are sutured to the superior portion of the tarsal plate. This surgery preserves levator muscle, Müller's muscle, and Whitnall's ligament without altering the structures that produce the three-layer tear film. In 69 eyelids operated on between July 1976 and July 1986, in which a minimum of 1 year of follow-up by one of use was obtained, results have been satisfactory and directly related to levator function. We believe this technique to be anatomically and physiologically superior to "maximal levator resection" with similar long-term results. More recent results have shown that the addition of a 5-mm superior tarsectomy provides an additional elevation of 1 to 1.5 mm. Whitnall's sling is best suited for cases where the opposite fissure height is 9 mm or less and levator function of the ptotic eyelid is 3 to 5 mm.

Adolescent↗
PubMed1990

Central nervous system damage and other anomalies in surviving fetus following second trimester antenatal death of co-twin. Report of four cases and literature review.

Four cases of multiple gestation with second trimester death of one fetus and subsequent damage to a survivor are reported. Monochorionic placentation was documented in three of the cases. Central nervous system lesions occurred in all cases, and bowel injury was noted in two of the damaged fetuses. Although rare maternal clotting problems have been reported in similar situations, none was noted in any of these four cases. Prior reports have indicated that losses in the first half of gestation were of no consequence to the surviving fetuses. These four cases contradict this suggestion, and indicate that close sonographic observation of the survivors is important in any multiple gestation where on fetus has died.

Abnormalities, Multiple↗
PubMed1990

Fetal intervention in obstructive uropathy: prognostic indicators and efficacy of intervention.

Management of the fetus with bilateral hydronephrosis is controversial; ability to predict outcome and efficacy of prenatal intervention are unknown. We studied 40 fetuses referred for ultrasonography, examination of fetal urine, and possible therapy. We retrospectively assigned fetuses to a good prognosis group if fetal urine was hypotonic (sodium less than 100 mEq/L, chloride less than 90 mEq/L, osmolarity less than 210 mOsm/L) and there was no ultrasonographic evidence of dysplasia; we assigned fetuses to a poor prognosis group if even one criterion was abnormal. Survival was greater in the good prognosis group than in the poor prognosis group (81% vs 12.5%; 87% vs 30%, excluding abortions) (p less than 0.005). We then attempted to assess the efficacy of prenatal urinary decompression by comparing outcome within the good and poor prognosis groups. Survival with intervention was greater in both the good prognosis group and the poor prognosis group (89% vs 70% and 30% vs 0%). In 6 of the 8 survivors in the good prognosis group, severe oligohydramnios was reversed by decompression. We conclude the fetal urine electrolyte levels and ultrasonographic appear helpful in predicting residual fetal renal function and neonatal outcome and that prenatal decompression may prevent the development of fatal pulmonary hypoplasia.

Amniotic Fluid↗
PubMed1990

Death due to high-output cardiac failure in fetal sacrococcygeal teratoma.

Fetal sacrococcygeal teratoma (SCT) is being recognized with increasing frequency. Placentomegaly and hydrops fetalis are preterminal events, and it has been suggested that fetal death may be due to high-output cardiac failure from arteriovenous shunting through the tumor. We had a chance to examine this hypothesis when a 21-week fetus presented with a huge sacrococcygeal teratoma. There were marked placentomegaly, cardiomegaly, hyperdynamic ventricles, and a pericardial effusion. Doppler studies showed tremendous flow through the SCT with extreme enlargement of the inferior vena cava, consistent with congestive heart failure from increased flow through the tumor. Hydrops developed, and the fetus was delivered because of placental abruption. This case provides supportive evidence that the teratoma acts as a large arteriovenous shunt, causing high-output cardiac failure. We have now collected 18 more cases of sacrococcygeal teratoma diagnosed in utero. Of the total 45 cases of fetal SCT, 9 had placentomegaly and/or fetal hydrops and all 9 fetuses died in utero or shortly after birth. We conclude that the only hope for survival in these severely affected fetuses is to reduce blood flow to the tumor before birth.

Cardiac Output↗