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Biomedical subjects

D Horton

Publications and source records attributed to D Horton.

At least 55 records · Page 3Linked to original sources
PubMed1990

Fluid flow performance of a new siphon-control device for ventricular shunts.

Most available cerebrospinal fluid diversion systems utilize differential-pressure valves that often induce overshunting, resulting in complications due to the siphoning of fluid from the ventricular system when the patient is in the erect position. A new siphon-control device (SCD) was tested alone and in combination with four types of differential-pressure valves with low, medium, and high opening pressures (namely PS Medical, Heyer-Schulte, Cordis-Hakim, and Codman valves). The valve inlet and outlet pressures were measured at several fluid inflow rates between 2.0 and 50.0 ml/hr. Inlet pressure and valve resistance were determined when the outlet pressures of the differential-pressure valve or SCD were varied between 0 and -60 cm H2O. Of the differential-pressures valves tested, none provided protection against siphoning without the distal connection of the SCD. The SCD allowed all differential-pressure valves tested to maintain atmospheric pressure regardless of the outlet pressure. The SCD performs in a manner similar to the older anti-siphon device, but with some improvements in design and construction. The results of this investigation suggest that the increased resistance due to the inline SCD is not functionally significant when added to the conventional valve systems with low opening pressure.

Cerebrospinal Fluid Shunts↗
PubMed1990

4-Demethoxy-3'-N-trifluoroacetyldoxorubicin. Synthesis and solid tumor activity.

A new route has been developed for the preparation of 3'-N-protected doxorubicin analogues. 4-Demethoxy-3'-N-trifluoroacetyldoxorubicin (5) was synthesized in an approach to an orally active anthracycline analogue. Tested against the B-16 murine solid tumor in mice, this compound increased life span by 133% when it was administered intraperitoneally at 25 mg/kg, and by 52% when it was given orally at 50 mg/kg.

Animals↗
PubMed1989

Confirmation of the structures of the products obtained on acylation of 2-amino-2-deoxy-D-gluconic acid.

Acetylation of 2-amino-2-deoxy-D-gluconic acid (1) with acetyl chloride-pyridine gave 2,3-unsaturated six- and five-membered lactones (2 and 3). Their benzoylated analogs (4 and 5) were obtained by benzoylation of 1 with benzoyl chloride-pyridine. Reaction of 1 with hot acetic anhydride-sodium acetate gave a approximately 1:2 mixture of (E)- and (Z)-2-acetamido-6-acetoxyhexa-2,4-dien-4-olide (6-E and 6-Z). Treatment of 3 with 1,8-diazabicyclo[5.4.0]undec-7-ene also gave as the main product 6-Z, which was isolated crystalline from the reaction mixture. The same reaction applied to compound 5 gave selectively the Z-isomer of the benzoylated furanone 7. Partial and total hydrogenation (H2-Pd-C) of the mixture 6-E, Z gave, respectively, a racemic monounsaturated lactone (8) and a dideoxy lactone (9), for which the threo-configuration for the chiral centers at C-2 and C-4 was determined. Acidic removal of the acetyl groups from 9 afforded the 2-amino-6-hydroxy-1,4-lactone hydrochloride 10. On the other hand, acetylation at high temperature of the 4,6-O-benzylidene derivative of 1 (11) gave the 2,3-unsaturated, six-membered lactone (12), precursor of 2-acetamido-6-acetoxyhexa-2,4-dien-5-olide (14).

Acetylation↗
PubMed1989

Preparative synthesis of C-(alpha-D-glucopyranosyl)-alkenes and -alkadienes: Diels-Alder reaction.

The reaction of 2,3,4,6-tetra-O-benzyl-1-O-(p-nitrobenzoyl)-alpha-D-glucopyranose with (E)-penta-2,4-dienyltrimethylsilane and boron trifluoride etherate in acetonitrile afforded stereoselectively (E)-5-(tetra-O-benzyl-alpha-D-glucopyranosyl)-1,3-pentadiene in good yield. The readily available penta-O-benzoyl-alpha-D-glucopyranose reacted with allyltrimethylsilane in the presence of boron trifluoride etherate in acetonitrile to give 3-(tetra-O-benzoyl-alpha-D-glucopyranosyl)-1-propene and its beta anomer in yields of 60% and 2.3%, respectively. Diels-Alder cycloaddition of maleic anhydride to diene 1 afforded the adduct cis,cis-3-(tetra-O-benzyl-alpha-D-glucopyranosylmethyl)cyclohex -4-ene- 1,2-dicarboxylic anhydride in high yield.

Alkadienes↗
PubMed1989

Primary radiation therapy in the treatment of squamous cell carcinoma of the soft palate.

From 1970 to 1986, 45 patients received primary radiation therapy for squamous cell carcinoma of the soft palate at the University of California Los Angeles (UCLA) Center for the Health Sciences and Wadsworth Veteran's Administration Hospital. Seven patients were lost to follow-up or had prior irradiation, and were excluded. Thirty-eight patients received a median dose of 70 Gy (62.5 to 80 Gy) to the primary site. After a median follow-up of 48 months, initial control of disease at the primary site was accomplished in 74% of the patients. The initial control by stage was as follows: TI, 83%, T2, 67%; and T3, 63%. After surgical salvage, local control increased to 92%, 80% and 75% for stages T1, T2, and T3, respectively. Twenty-nine percent (11 of 38) of the patients had cervical node metastases at presentation. Radiation provided regional control in 96% (26 of 27) with N0 disease and 86% (six of seven) with N1 disease at diagnosis. Sixteen patients (42%) had an additional malignancy of the upper aerodigestive tract. Because the incidence of second malignancies after treatment is high and surgical salvage of treatment failures is possible, close follow-up is essential in the management of this tumor. We conclude that radiation therapy is an effective modality for the treatment of squamous cell carcinoma of the soft palate. Primary radiation therapy may offer many patients the chance to avoid surgical procedures that are both cosmetically and functionally debilitating without compromosing treatment outcome.

Adult↗
PubMed1989

Malignant salivary gland tumors of the paranasal sinuses and nasal cavity. The UCLA experience.

Between 1962 and 1985, 35 patients with malignant salivary gland tumors of the paranasal sinuses and nasal cavity were treated with curative intent at UCLA. They were staged according to the American Joint Committee (TNM) classification for squamous cell carcinoma of the paranasal sinuses: 27 of 35 (77%) patients presented with T3-4 disease. Adenoid cystic carcinoma was the diagnosis in 24 (68%) patients, while adenocarcinoma accounted for half of the cases involving the ethmoid sinuses and nasal cavity. Eleven patients were treated with surgery alone, 13 with combined surgery and radiation, and 11 with radiation therapy alone. All patients were followed from 40 to 216 months. Analysis by treatment modality revealed a local control of 18% (2 of 11) in the surgery alone group, 62% (8 of 13) in the combined group, and 9% (1 of 11) in the radiation alone group. The group undergoing combined treatment achieved the highest local control rate despite having a higher proportion of patients with advanced stage and residual disease at the surgical margins. In patients with positive surgical margins, the tumor recurred locally in 4 of 6 (67%) unirradiated patients, compared with 3 of 10 (30%) of those undergoing postoperative irradiation. Patients with adenoid cystic carcinoma had poorer results, with only 25% remaining relapse-free, compared with 45% of patients with adenocarcinoma. The 5-, 10-, 15-, and 20-year actuarial survival for all cases was 73%, 60%, 32%, and 20%, respectively. We conclude that post-operative radiation improves the results of treatment in all patients with malignant salivary gland tumors in this location, compared with the results of surgery alone.

Adenocarcinoma↗
PubMed1989

Spina bifida occulta: early clinical and radiographic diagnosis.

Tethered cord syndrome (TCS) is produced by traction of the lumbosacral spinal cord. Clinically, patients with tethered cord syndrome present with various combinations of neurologic, orthopedic, and cutaneous abnormalities. These abnormalities are often subtle. Early diagnosis, and treatment when indicated, is essential to prevent progressive and frequently irreversible neurological deterioration. Early diagnosis is aided by a high degree of clinical suspicion. Plain spine films are useful in the preliminary evaluation of suspected dysraphism. When plain film abnormalities are present, magnetic resonance imaging (MRI) has been found to be the single most effective procedure for both initial diagnosis and pre-operative evaluation of patients with myelodysplasia.

Diagnosis, Differential↗
PubMed1988

Stereoselective syntheses of C-(D-glucopyranosyl)alkenes.

alpha-D-Glucopyranose pentaacetate (1) was found to undergo stereoselective conversion in good yield into 3-(tetra-O-acetyl-alpha-D-glucopyranosyl)-1-propene (4) by treatment with allyltrimethylsilane and boron trifluoride etherate in acetonitrile. Similar treatment of methyl tetra-O-acetyl-alpha-D-glucopyranoside or tetra-O-acetyl-alpha-D-glucopyranosyl bromide also gave 4 in preference to its beta anomer, but net yields were lower. Similar reaction of 1 with (E)-penta-2,4-dienyltrimethylsilane afforded the readily polymerizable 5-(tetra-O-acetyl-alpha-D-glucopyranosyl)-(E)-1,3-pentadiene, accompanied by a minor proportion of its beta anomer.

Alkenes↗
PubMed1986

Cross-reactions of lipopolysaccharides of Pseudomonas aeruginosa in antipneumococcal and other antisera.

Lipopolysaccharides of the seven Fisher immunotypes of Pseudomonas aeruginosa gave cross-precipitation in many antipneumococcal sera. The reaction of Pseudomonas type IV in type 25 antipneumococcal serum was immediate and heavy: 93 micrograms of antibody nitrogen per ml. Correlations are described, mainly between the structures of the O-chains of the immunotypes and their specificities as shown by the cross-reactions.

Antibodies, Bacterial↗
PubMed1985

Synthesis and antitumor activity of 2'-bromo- and 2'-chloro-3'-acetoxy-3'-deaminodaunorubicin analogs.

Bromination of 3,4-di-O-acetyl-L-rhamnal (7) and subsequent glycosidic coupling under Koenigs-Knorr conditions with daunomycinone gave a mixture of three compounds having the beta-L-gluco (10), alpha-L-gluco (11), and alpha-L-manno (12) configurations. Analogous bromination of 3,4-di-O-acetyl-L-fucal (13) followed by coupling with daunomycinone gave a mixture of three glycosides having the beta-L-galacto (16), alpha-L-galacto (17), and alpha-L-talo (18) configurations. Chlorination of 7 and coupling with daunomycinone in the presence of silver triflate gave products having the alpha-L-gluco (21) and alpha-L-manno (22) configurations, whereas 13, under similar conditions, gave only one stereoisomeric product, that having the alpha-L-galacto (24) configuration. Compounds 12 and 22 showed high in vivo activity in the P-388 lymphocytic leukemia assay.

Animals↗
PubMed1985

Selective acylation of 6-deoxyglycals.

L-Rhamnal was acylated under a variety of conditions with various acylating reagents. Substitution of the hydroxyl group in the allylic position was favored when acetyl chloride, N-acetylimidazole, benzoyl chloride, and N-benzoylimidazole were used (40-60% net yields), whereas the homoallylic group of L-rhamnal was selectively protected when acetic anhydride-pyridine was employed for the acylation. The monoacetates of L-fucal underwent O-3----O-4 migration of the acetyl group, and selective acylation of this glycal could not be achieved.

Acylation↗