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Biomedical subjects

R Koller

Publications and source records attributed to R Koller.

70 records · Page 4Linked to original sources
PubMed1990

Ipsilateral and cross-over elongation of the motor nerve by nerve grafting: an experimental study in sheep.

In difficult reconstructions, ipsilateral or cross-over nerve grafting is sometimes necessary to achieve reinnervation and motor function. This experimental study in sheep was to answer the question of limitation of elongation of a motor nerve by grafting, the question of the optimal time for suturing the nerve graft to the muscle nerve, and the question of the successful application of this surgical technique in extremities. In 18 sheep, the vastus nerve was elongated by a saphenous nerve graft as long as possible up to 30 cm (step 1). In 10 animals the nerve graft was applied ipsilaterally, and in 8 animals it was used as a cross-over nerve graft to the contralateral limb. The time between nerve grafting and connection of the distal end of the nerve graft to the freshly cut rectus nerve supplying the rectus femoris muscle (step 2) was variable: 0, 3, 6, 9, and 12 months. In all animals, the final experiments (step 3) were performed 6 months after the last operation (step 2). Muscle force measurements in the rectus femoris muscle and quantitative analysis of the number and diameter of myelinated nerve fibers in cross sections of the nerve biopsies at different levels showed that elongation of a motor nerve by nerve grafting is principally not limited. The functional results were rather inhomogeneous and therefore unpredictable (ipsilateral group: maximum tetanic tension = 27 to 172 N; cross-over group: 0 to 227.5 N). Nevertheless, crossover nerve grafting is recommended for selected cases even in extremities. There was no correlation between the time interval between the two operations and the functional or morphologic results, although better functional results were obtained when the distal nerve suture (step 2) was performed some months after nerve grafting (step 1). A clear correlation was found only between the number of regenerated axons in the rectus nerve behind the second suture line and the muscle function.

Animals↗
PubMed1990

Regions of the Moloney murine leukemia virus genome specifically related to induction of promonocytic tumors.

Moloney murine leukemia virus (MuLV) can be a potent inducer of promonocytic leukemias in mice that are undergoing a chronic inflammatory response. The neoplasms are, at least in part, associated with insertional mutagenesis of the c-myb locus. Evidence is presented for the existence of at least two genetic elements of the virus that are crucial to induction of this disease but are not required for viral replication in hematopoietic tissues or induction of lymphoid disease. These genetic elements were detected by testing the pathogenicity of recombinants between Moloney and Friend MuLVs, the latter of which is nonleukemic to myeloid cells under these conditions, and by testing Moloney MuLV-based viruses that have nonretroviral sequences inserted at specific endonuclease sites in their long terminal repeats (LTRs). Analysis of the Moloney/Friend recombinants showed that there are sequences within the structural gene domain of Moloney, but not Friend, MuLV that are necessary for promonocytic leukemia, whereas the LTRs of the MuLVs are equally effective for promonocytic tumor formation and insertional mutagenesis of the c-myb gene. Experiments with viruses which were mutagenized in the LTR by insertions demonstrated that there is a specific genetic element in the U3 region of the LTR of Moloney MuLV, upstream of the 75-base-pair enhancer which, when interrupted, results in loss of leukemogenicity for cells in the monocytic lineage but not cells in the lymphoid lineage. We conclude, therefore, that promonocytic leukemia induction, in Moloney MuLV-infected mice undergoing a chronic inflammatory response, requires specific sequences in the structural gene region of Moloney MuLV as well as other sequences in the regulatory region of the virus.

Animals↗
PubMed1984

Nucleotide sequence of two rasH related-genes isolated from the yeast Saccharomyces cerevisiae.

A complete nucleotide sequence of two ras-related yeast genes (c- rassc -1 and c- rassc -2) isolated from the yeast strain Saccharomyces cerevisiae is reported. They encode predicted polypeptides of 40,000 and 41,000 daltons, respectively. The N-terminal 170 amino acids from both genes show extensive amino acid homology to other ras genes from vertebrates, whereas their C-termini have diverged. These genes should be useful in the elucidation of a normal biological function of ras-related genes in a simple system like yeast.

Amino Acid Sequence↗
PubMed1983

The human c-ras1H oncogene: a mutation in normal and neoplastic tissue from the same patient.

The c-ras1H oncogene can be distinguished from its normal cellular counterpart by the loss of a restriction endonuclease site. This sequence alteration is the basis of a rapid screening method for the presence of this oncogene. DNA's from 34 individuals were screened by this method, and all were homozygous for the normal allele. In contrast, DNA from a patient's bladder tumor, as well as DNA from his normal bladder and leukocytes, were heterozygous at that restriction endonuclease site. Further restriction enzyme mapping pinpointed the change in the mutant allele as being one of two nucleotides, either of which would change the 12th amino acid (glycine) in the normal c-ras1H gene product. Point mutations in the codon for this amino acid have previously been described in a bladder tumor cell line and in the viral oncogene v-rasH. These results indicate that the patient carried a c-ras1H oncogene in his germ line, raising the possibility that the c-ras1H oncogene confers a predisposition to neoplasia.

Base Sequence↗
PubMed1982

Monoclonal antibody to spleen focus-forming virus-encoded gp52 provides a probe for the amino-terminal region of retroviral envelope proteins that confers dual tropism and xenotropism.

Monoclonal antibodies which recognize a region common to Friend spleen focus-forming virus encoded gp52 and Friend mink cell focus-inducing viral gp70 were isolated. One such antibody from hybridoma 7C10 was tested extensively in immune precipitation and was found to react with a determinant on envelope gp70s of all mink cell focus-inducing, xenotropic, and amphotropic mouse retroviruses tested, but not with envelope gp70s of ecotropic viruses, including Friend, Moloney, and AKR murine leukemia viruses. Monoclonal antibody from hybridoma 7C10 precipitated a 23,000-molecular-weight fragment, derived by V8 protease digestion of Friend mink cell focus-inducing gp70. This 23,000-molecular-weight peptide was determined to derive from the amino terminus of the molecule. These results correlate well with other genetic data which indicate that endogenously acquired sequences of mink cell focus-inducing viruses are found at the 5' end of the envelope gene.

Antibodies, Monoclonal↗
PubMed1982

Low back pain comprehensive rehabilitation program: a follow-up study.

The outcome of the management of chronic low back pain in 42 men and 36 women by a comprehensive rehabilitation program consisting of biofeedback training, counseling in self-control techniques, self-regulated medication reduction, physical therapy, vocational rehabilitation services and education conducted in a therapeutic milieu was examined at 6 months and 12 months after discharge. The mean age of the subjects was 43.4 years: the mean highest school grade completed, 12.6; and the mean full scale WAIS IQ, 106.7. On admission 72 were unemployed and had been disabled and unemployed for a median time for 3 years. Almost two-thirds were involved in litigation. Thirty-three were working or accepted for employment t 6 months after discharge and 35 at 12 months (p less than 0.001). Success rates are higher when only those who stayed in the program for more than 4 weeks are considered. The employed patients rated their pain lower, used less medication and relied less on attention from physicians. They did not seem to differ in their use of relaxation skills or exercise. A similar study has been initiated of patients randomly assigned to treatment and waiting list control groups.

Adult↗
PubMed1981

Computerized tomography and pure sensory stroke.

We studied three patients fitting the clinical syndrome of "pure sensory" stroke. The abnormalities on computerized tomography (CT) scan differed and included posterior cerebral artery occlusion, lacunar infarct in the thalamocortical pathway, and hemorrhage in the thalamus. These cases were unique in that CT scan abnormalities were found in patients with pure sensory stroke.

Aged↗
PubMed1979

An innovative program for the restoration of patients with chronic back pain.

The literature on conventional medical procedures for restoring high-risk patients having chronic low back pain reveals that these procedures are ineffective and may even be iatrogenic. An alternative, noninvasive approach, which takes into consideration the critical role of cognitive and emotional factors, is practiced at Casa Colina Hospital for Rehabilitative Medicine. Details of the approach as well as comments confirming its efficacy are presented.

Analgesics↗
PubMed1977

Comprehensive rehabilitation of patients having chronic low back pain.

Seventy-two patients having chronic back pain, representative of high-risk demographic and personality populations, received a broad range of therapeutic modalities designed around the theme of self-regulation. The self-regulation principle was used in: (1) biofeedback training for teaching self-regulated muscle relaxation; (2) psychological counseling emphasizing self-control techniques for the management of stress and anxiety, including assertion training; (3) patient-regulated medication program; (4) patient involved case conferences; (5) physical therapy program emphasizing reconditoning; (6) comprehensive vocational rehabilitation services; (7) a series of educational lectures; (8) a therapeutic milieu designed for relaxation, recreation and socialization. Utilizing a success criteria of functional physical activity at discharge (average length of stay, 45 days) and levels of vocational restoration (employable, in training, or employed at 30 days postdischarge), 57 of the patients demonstrated unimpaired physical functioning levels and 59 of the patients were at success levels of vocational restoration.

Adult↗
PubMedDate not supplied

Three genes with different functions in transformation are regulated by c-Myb in myeloid cells.

The proto-oncogene c-myb is constitutively expressed in murine leukemia virus-induced myeloid leukemia (MML) due to the integration of virus at this locus. Our recent focus has been the determination of genes regulated by this transcription factor that may be involved in transformation. Data presented here, using conditional expression of Myb in myeloid cells, show that c-Myb directly transactivates the endogenous c-myc and Bcl-2 genes, which explains at least in part how c-Myb regulates proliferation and survival. In addition, c-Myb prevents expression at the RNA level of the tumor suppressor INK4b gene. This gene encodes a cyclin-dependent kinase inhibitor, p15INK4b, that is normally upregulated at the mRNA level during myeloid differentiation and promotes growth arrest. The MMLs are generally characterized as differentiated monocytic tumors and possess the phenotype that is normally associated with p15INK4b expression. c-Myb inhibits expression of this gene, however, and therefore acts to promote a pathway which is abnormal in mature cells. This activity of c-Myb collaborates with its maintenance of c-myc expression to promote growth.

Animals↗
PubMedDate not supplied

ras-Related gene sequences identified and isolated from Saccharomyces cerevisiae.

The oncogenes of Harvey and Kirsten murine sarcoma viruses (v-rasH and v-rasK) and their cellular homologues (c-rasH and c-rasK) constitute two members of the ras gene family. Each functional member of the ras gene family encodes a 21,000 molecular weight protein (p21ras). ras genes have been detected in a wide variety of vertebrate species, including Xenopus laevis (R. E. Steele, personal communication), and in Drosophila melanogaster. We report here the detection of ras-related genes in the yeast Saccharomyces cerevisiae, and the isolation of two ras-related molecular clones, c-rassc-1 and c-rassc-2, from the DNA of Saccharomyces. Both c-rassc-1 and c-rassc-2 hybridize specifically to probes prepared from mammalian ras DNA. Sequencing of c-rassc-1 reveals extensive amino acid homology between the protein encoded by c-rassc-1 and the p21 encoded by c-rasH. Our studies suggest that these clones can be used to elucidate the normal cellular functions of ras-related genes in this relatively simple eukaryotic organism.

Amino Acid Sequence↗