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Biomedical subjects

M Jacobs

Publications and source records attributed to M Jacobs.

At least 145 records · Page 8Linked to original sources
PubMed1992

Management of the subluxed crystalline lens.

There has been a traditional reluctance to remove a subluxed (ectopic) lens because of the high surgical risk. The use of closed intraocular microsurgical techniques, however, now allows greater intraoperative control with few complications. The authors present the results of subluxed lens extraction, by limbal or pars plana lensectomy, in 44 eyes of 24 patients, in which the indication for surgery was lens subluxation causing a reduction in visual acuity or uncorrectable refractive error. Visual acuity was improved in all cases after surgery, with no significant complications. Patients with reduced visual acuity secondary to ectopic lenses have a good visual prognosis after lensectomy using a closed intraocular microsurgical technique.

Adult↗
PubMed1992

Placement of drains in laparoscopic procedures.

The technique of laparoscopic cholecystectomy is, in many areas, replacing the standard open cholecystectomy as the method of choice. Many surgeons are accustomed to the use of peritoneal drainage following cholecystectomy. The authors have developed a simple, effective, and rapid, yet controlled method of placing drains into the abdominal cavity, using laparoscopic techniques.

Cholecystectomy↗
PubMed1992

Analysis of splice sites in the early region of bovine polyomavirus: evidence for a unique pattern of large T mRNA splicing.

The genetic organization of the early region of bovine polyomavirus (BPyV) was studied by analysis of the splice sites used in early mRNA maturation, using reverse transcription-polymerase chain reaction and DNA sequencing techniques. When compared to other polyomaviruses, the BPyV early region appears to have an uncommon organization. In the major early mRNA molecule two small intron sequences of 71 and 77 nucleotides, separated from one another by an 80 nucleotide exon sequence, were identified. Through splicing out both introns, a mRNA molecule is generated that contains an open reading frame with the capacity to encode 619 amino acids. Comparisons with the simian virus 40 large T antigen suggested that this mRNA molecule encodes the BPyV large T antigen. Remarkably, no mRNA product encoding a protein with a size comparable to that of the small t antigens of other polyomaviruses was detected. Another transcript was observed from which only the 77 nucleotide intron sequence had been removed, thereby creating a mRNA molecule with the capacity to encode only 45 amino acids. Whether this mRNA product represents a mature transcript which is translated in BPyV-infected cells or is an intermediate in the formation of the large T mRNA molecule is not known. Analysis of BPyV-specific early mRNA products isolated from BPyV-transformed murine cells revealed only the amplification product representing the putative large T antigen transcript.

Amino Acid Sequence↗
PubMed1992

The objective assessment of abnormal eye movements in infants and young children.

Recordings of eye movements from infants and young children can be of clinical value in patients with certain neuro-ophthalmological problems. This requires that the characteristics of normal eye movements in this same age-group are known. Using an electro-oculographic technique in a specially developed laboratory we have been able to assess the saccades, binocular and monocular smooth pursuit, binocular and monocular optokinetic nystagmus (OKN), and sustained vestibular rotation in infants and young children; these recordings were performed in one session lasting approximately 35 minutes. The recordings from four children with abnormal eye movements (delayed visual maturation, hemicerebral cyst, congenital ocular motor apraxia, and gaze-paretic nystagmus) are briefly reported and compared to normal eye movements of age-related children. The limitations of this procedure are discussed.

Adolescent↗
PubMed1992

Oxidative modification of low-density lipoproteins and the inhibition of relaxations mediated by endothelium-derived nitric oxide in rabbit aorta.

1. The mechanism by which Cu(2+)-oxidized low-density lipoproteins (oxLDL) inhibit acetylcholine (ACh)-evoked relaxations mediated by endothelium-derived nitric oxide (EDRF) in rabbit aortic rings was investigated. The proposed role of lysophosphatidylcholine (LPC) in the inhibition was also studied. 2. The kinetics of lipid peroxidation of native low-density lipoproteins (LDL) from individual donors, as measured by changes in conjugated diene concentration, were related to the inhibitory effects of the resultant oxLDL. It was found that the more susceptible LDL was to oxidation, the greater the inhibition. 3. No correlation was found between the inhibitory effects of oxLDL and LPC content. 4. Synthetic 1-palmitoyl LPC produced an inhibition of ACh-induced relaxations and when added to precontracted rings evoked nitric oxide-mediated endothelium-dependent relaxation. This latter effect was not elicited by oxLDL. 5. Synthetic 1-palmitoyl (10 microM) had no effect on relaxations evoked by glyceryl trinitrate in endothelium-denuded aortic rings in contrast to the inhibition found previously for oxLDL. 6. Concentrations of oxLDL and phospholipase A2-treated LDL which inhibited relaxation contained very different LPC concentrations. Unlike oxLDL, the inhibitory effects of phospholipase A2-treated LDL preparations were independent of the donors and showed no lag period. 7. We suggest that there are differences in the mechanisms by which oxLDL and 1-palmitoyl LPC exert their inhibitory effects on relaxation. 8. The inhibition of relaxation by oxLDL (1-2 mg protein ml-1) was prevented by the presence of high-density lipoproteins (HDL; 1-2 mg protein ml-1).9. It is proposed that prevention of the inhibition of relaxation by HDL is consistent with the inhibitory factor(s) being lipophilic constituents of oxLDL. However, variations in the inhibitory effects of oxLDL preparations are not due to differences in their LPC content and factors other than LPC must contribute to the inhibition.

Animals↗
PubMed1992

Eye movement tics.

An 8-year-old girl presented with opsoclonus-like eye movement and an 18 month history of intermittent facial tics. Investigations were all normal. Electro-oculography showed the eye movements to be of variable amplitude (10-40 degrees), with no intersaccadic interval, and with a frequency of 3-4 Hz. Saccades, smooth pursuit, optokinetic, and vestibular reflexes were all normal. These abnormal eye movements eventually disappeared. It is thought that they were a form of ocular tics.

Child↗
PubMed1992

Simultaneous treatment with single-agent chemotherapy and radiation for locally advanced cancer of the head and neck.

A substantial proportion of patients with squamous cell carcinoma of the head and neck have extensive locoregional disease at presentation. While extensive surgical procedures may completely eradicate local disease with acceptable morbidity for smaller tumors, in patients with stage III and IV disease, high local relapse rates and relatively short survival times still characterize the course of the majority of such patients. For patients with locally unresectable disease, the combined use of chemotherapy and radiation has resulted in encouraging data both in terms of local control and survival. Combined-modality programs frequently employ platinum coordination complexes, and standard or hyperfractionated radio-therapy toxicity data suggest that the overall tolerance of such programs is acceptable and, more important, long-term follow-up has shown that function can be largely preserved. In this review we illustrate the experience with combined single-agent chemotherapy and radiotherapy, and discuss the methodologic difficulties of clinical trials in this setting. We describe our experience with combined carboplatin and simultaneous conventional radiation in patients with extensive unresectable locoregional disease. Encouraging results and modest toxicity clearly support further testing with this approach, especially in patients with less advanced and bulky disease.

Aged↗
PubMed1992

[Selenium poisoning in fattening swine].

A case of selenium toxicosis was observed in fattening pigs. Intoxication was caused by high levels of selenium in a commercial mineral premix. Instead of the recommended dose of 16 ppm Se, the mineral feed contained selenium at concentrations of 657 and 1059 ppm. The ration in use was found to contain more than 14 ppm selenium. Clinical symptoms were observed 5 to 6 weeks after the pigs began consuming the contaminated feed mixture. Feed intake was markedly reduced and animals showed severe lameness due to separation and necrosis of the hoof wall at the coronary band. Some pigs were reluctant to stand. In some cases alopecia was detected. At histopathological examination one animal with paralysis of the hind limbs revealed a focal bilaterally symmetric poliomyelomalacia in the lumbar segment of the spinal cord. Diagnosis was confirmed by high selenium contents of liver, kidneys and blood. After removing the incriminated feed no further pigs developed signs of intoxication. New horn growth was present and lame animals recovered slowly.

Alopecia↗
PubMed1992

Plant protoplasts as genetic tool: selectable markers for developmental studies.

Protoplasts have usually been presented as a methodological tool. Even as such, they make possible an impressive array of applications in plant biology. Here we report on the use of protoplast-derived selectable markers in the study of several disturbed genetic systems with obvious effects on plant development: (1) auxotrophic mutants and the control of amino acid biosynthesis and transport in vegetative and reproductive tissues; (2) introgression of alien genetic information across phylogenetic boundaries by protoplast fusion, a consequence of controlled dedifferentiation-redifferentiation processes and attenuated incompatibility reactions in cultured cells; (3) expression (in)stability of foreign genes in transgenic plants during successive meiotic generations and in crosses between independent transformants.

Cells, Cultured↗
PubMed1991

The modulation of ferryl myoglobin formation and its oxidative effects on low density lipoproteins by nitric oxide.

This study has investigated the interactions between nitric oxide and haem protein radicals. The results demonstrate that nitric oxide interacts with activated ferryl myoglobin species with reduction to metmyoglobin, but the extent and duration of the reduction depends on the relative concentrations of nitric oxide and hydrogen peroxide. Ferryl myoglobin has a much greater relative potential for oxidising polyunsaturated fatty acid side chains in low density lipoproteins than in cell membranes. The peroxidative response can be modulated by nitric oxide: ferryl myoglobin-mediated peroxidation of LDL may be enhanced or suppressed by nitric oxide depending on the relative concentrations of NO and hydrogen peroxide.

Erythrocyte Membrane↗
PubMed1991

Highly bioluminescent Bacillus subtilis obtained through high-level expression of a luxAB fusion gene.

Bioluminescence levels comparable to those achievable in Escherichia coli have yet to be obtained from luxAB expression in gram-positive bacteria. In this communication we describe the gene engineering required to generate a highly bioluminescent derivative of Bacillus subtilis. The combination of a powerful promoter, Pxyn, a fusion derivative of luxAB from Vibrio harveyi and translational coupling have overcome the previously reported limitations in luxAB expression. The implications for highly bioluminescent gram-positive organisms are discussed.

Bacillus subtilis↗
PubMed1991

The effects of a 0.12% chlorhexidine gluconate mouthrinse on orthodontic patients aged 11 through 17 with established gingivitis.

The purpose of this study was to assess the effectiveness of a 0.12% chlorhexidine gluconate (CH) mouthrinse, Peridex, on orthodontic patients 11 through 17 years of age with established gingivitis. Thirty-four subjects were divided into two groups (CH and placebo) of 17 subjects each on the basis of gender, and they were evaluated at baseline, at 6 weeks, and at 12 weeks in a double-blinded manner. The gingival index (GI) of Löe and Silness, the plaque index (PI) of Silness and Löe, the Eastman Interproximal Bleeding Index, and the CWRU staining index were recorded for each subject. The subjects in the CH group, as compared with the placebo group, had statistically significant reductions, expressed as percent reductions against baseline, at the conclusion of this 3-month period: PI = 64.9%, GI = 60.0%, and gingival bleeding = 77.2%. Staining was in the moderate range, and it was concentrated on the mandibular lingual surfaces. Peridex, in combination with mechanical plaque removal, proved to be an important therapeutic agent in controlling gingival inflammation, bleeding, and plaque accumulation in orthodontic patients 11 through 17 years of age with established gingivitis.

Adolescent↗
PubMed1991

The systemic and genetic significance of congenital optic disc anomalies.

Optic disc anomalies have great significance as a clue to associated systemic problems and as a marker of inherited disease. Optic nerve hypoplasia and colobomas of the optic disc are the main visually significant disorders; however, the Morning Glory disc anomaly and Aicardi's syndrome may also be associated with visual impairment.

Coloboma↗
PubMed1991

Laparoscopic cholecystectomy in acute cholecystitis.

The experience of laparoscopic cholecystectomy in 79 patients with acute cholecystitis is described. This group is subdivided into acute and severe acute cholecystitis. These categories are defined. Six percent of our patients with acute disease and 30% of our patients with severe acute disease were converted to open cholecystectomy. Those patients who were converted to open cholecystectomy are discussed. The four port technique and decompression of the gallbladder is described. We conclude that acute cholecystitis should not be a contra-indication to the well-trained laparoscopic surgeon.

Acute Disease↗
PubMed1991

Laparoscopic choledocholithotomy.

Common duct stones present a special problem to the surgeon when he performs a laparoscopic cholecystectomy. We describe a method of exploring the common duct and extracting stones. The procedures for opening of the common duct, removal of stones, and the placement of a T-tube are carefully outlined.

Catheterization↗