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J Koch

Publications and source records attributed to J Koch.

At least 109 records · Page 6Linked to original sources
PubMed1997

Padlock probes reveal single-nucleotide differences, parent of origin and in situ distribution of centromeric sequences in human chromosomes 13 and 21.

Chromosome centromeres, composed of repeated DNA sequences, orchestrate the correct segregation of chromatids in cell division. We have examined the centromeres of human chromosomes 13 and 21 by studying the distribution, in situ, of two alpha satellite sequences that differ in a single nucleotide position. This was possible using padlock probes, oligo-nucleotides that can be ligated into circles upon target recognition. The segregation of individual 13 and 21 homologues in a family was followed by monitoring of the signals from two differentially labelled probes, specific for either sequence variant. A characteristic arrangement of the repeat motifs in three separate spots, oriented transverse to the length axis of the metaphase chromosomes and bilaterally symmetric, indicates that only parts of the detected regions are involved in the centromeric region, joining the sister chromatids before anaphase.

Base Sequence↗
PubMed1997

Evaluation of the urinary cortisol: creatinine ratio in the diagnosis of hyperadrenocorticism in dogs.

The diagnostic accuracy of the urinary cortisol:creatinine ratio (CCR), with the cortisol being measured by ELISA, was evaluated by subjecting data from 18 dogs with and 20 dogs without hyperadrenocorticism to receiver operating characteristic (ROC) curve analysis. The area under the ROC curve (W 0.93, SE(w) 0.044) was much higher than 0.5, indicating that the CCR did distinguish between dogs with and without hyperadrenocorticism. A cutoff value of about 60 x 10(-6) was associated with the highest sensitivity (1.0) and specificity (0.85). At the disease prevalence rate of the present study (0.47), the positive and negative predictive values were 0.87 and 1.0, respectively. These numbers indicate that canine hyperadrenocorticism may be safely excluded when the CCR is below 60 x 10(-6) but that a test of higher specificity (eg, the ACTH stimulation test) should be used to confirm the diagnosis of canine hyperadrenocorticism when the CCR is above 60 x 10(-6).

Adrenocortical Hyperfunction↗
PubMed1997

Duplex Doppler measurements of renal blood flow in a dog with Addison's disease.

Abnormal intrarenal flow in a seven-year old female Tibetan terrier with Addison's disease was demonstrated by duplex Doppler examination. Abnormal flow may reflect renal vasoconstriction due to increased activity of the renin-angiotensin system. Although not pathognomonic, an increased resistive index (> 0.70) in an otherwise ultrasonographically normal kidney can be due to Addison's disease and the technique may prove valuable as a quick non-invasive tool in the management of this disease.

Addison Disease↗
PubMed1997

The monosomy 7 clone in interphase and metaphase cell population: a combined chromosome and primed in situ labeling study.

Loss of a chromosome 7 is associated with a poor prognosis in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). Some studies have shown higher frequencies of monosomy 7 (-7) in dividing than nondividing myeloid cells, which might indicate that -7 confers a proliferative advantage on the host cell. As other groups have not been able to confirm this, we compared the -7 frequencies in bone marrow metaphases as studied with conventional cytogenetics and in interphase cells using primed in situ (PRINS) labeling. We found significantly higher -7 frequencies in metaphase than in interphase cells irrespective of diagnosis and presence or absence of additional chromosome aberrations. Further, we found a significant correlation between the -7 percentages in resting and dividing cells. Finally, as our material showed a clear male preponderance, Mitelman's Catalog of Chromosome Aberrations in Cancer was searched for -7. Of 815 cases with AML or MDS, 491 (60.3%) were found to be men. To our knowledge, this is the first observation of a clear deviation from the 1:1 sex ratio in -7 patients.

Acute Disease↗
PubMed1997

Recurrent pyogenic cholangitis in Asian immigrants to the United States: natural history and role of therapeutic ERCP.

We reviewed the clinical presentation, cholangiographic features, and long-term outcomes in 41 patients with recurrent pyogenic cholangitis (RPC, "Oriental" cholangiohepatitis) who underwent ERCP at our institution, comparing patients who were initially managed with therapeutic ERCP, immediate hepatobiliary surgery, and no intervention. Patients undergoing only diagnostic ERCP had recurrent symptoms in 62% of cases, twice as often as patients managed initially by therapeutic ERCP or immediate surgery. These former patients required subsequent surgery more often than patients in the latter two groups. Outcomes for patients with diffuse biliary calculi were no different between patients managed by therapeutic ERCP or by immediate hepatobiliary surgery. In the 15 patients with only extrahepatic stones, 7/9 (71%) managed by therapeutic endoscopy and 7/8 (87.5%) managed by immediate hepatobiliary surgery were asymptomatic at almost two years mean follow-up (P > 0.05). Patients having undergone at least one definitive hepatobiliary surgery had fewer recurrences when managed by repeat surgery, although the difference was not statistically significant. Four of six (67%) patients with dominant strictures managed endoscopically are asymptomatic at mean follow-up of 15 months. Our study emphasizes the recurrent nature of symptoms in RPC and supports the primary role of therapeutic ERCP in managing these patients, especially those with extrahepatic stone disease alone.

Asia, Southeastern↗
PubMed1996

Molecular cloning and characterization of a full-length complementary DNA encoding human acid ceramidase. Identification Of the first molecular lesion causing Farber disease.

Human acid ceramidase ((AC) N-acylsphingosine amidohydrolase, EC 3.5. 1.23) hydrolyzes the sphingolipid ceramide into sphingosine and free fatty acid. Ceramide is an essential component of all sphingolipids and an important cell-signaling molecule. Moreover, an inherited deficiency of AC activity leads to the lysosomal storage disorder known as Farber disease. Human AC was purified from urine, and 117 amino acid residues were determined by microsequencing. Degenerative oligonucleotide probes were then constructed and used to screen for human fibroblast and pituitary cDNA libraries. Several partial cDNA clones were obtained, and two of these were combined to construct a full-length cDNA containing a 17-base pair (bp) 5'-untranslated sequence, a 1185-bp open reading frame encoding 395 amino acids, a 1110-bp 3'-untranslated sequence, and an 18-bp poly(A) tail. Transient expression of the full-length cDNA in COS-1 cells led to a 10-fold increase in AC activity. In addition, biosynthetic studies carried out in the transfected cells demonstrated that 13-kDa (alpha) and 40-kDa (beta) AC subunits were derived from a common 55-kDa precursor encoded by the full-length cDNA. This protein pattern was identical to that seen in normal human skin fibroblasts. A homoallelic point mutation (T222K) was also identified in the AC gene of a patient suffering from Farber disease, further confirming the authenticity of the full-length cDNA.

Acid Ceramidase↗
PubMed1996

NMDA receptor dependence of kindling and mossy fiber sprouting: evidence that the NMDA receptor regulates patterning of hippocampal circuits in the adult brain.

The NMDA receptor plays an important role in patterning neural connectivity in the developing brain. In the adult brain, repeated kindling stimulation of limbic pathways increases the NMDA-dependent component of synaptic transmission in granule cells of the dentate gyrus (DG) and also induces sprouting of the mossy fiber axons of granule cells that reorganizes synaptic connections in the DG. Because the NMDA antagonist MK801 impedes the progression of kindling, it was of interest to determine whether MK801 also modified mossy fiber sprouting. Low doses of MK801, which had no antiseizure effect, impaired the progression of kindling and development of mossy fiber sprouting during the initial and also more advanced stages of kindling. These observations demonstrate that the NMDA receptor is a component of a molecular pathway that influences the progression of kindling and mossy fiber sprouting and suggest that NMDA-dependent gene expression may play a role in the development of long-term structural and functional alterations induced by seizures in hippocampal circuitry. The NMDA receptor appears to play a continuing role in modifying the organization and patterns of connectivity in hippocampal circuits of the adult brain.

Age Factors↗
PubMed1996

Ultrasonographic determination of ascitic volume.

The purpose of this study was to develop a method by which ascitic volume can be calculated using transcorporeal ultrasonography, and to determine the accuracy of this method by comparison with the volume of distribution of a radiolabeled tracer (indicator dilution technique [IDT]). Subjects with ascites confirmed by ultrasonography were recruited from the San Francisco General Hospital Gastroenterology and Liver Clinics. With subjects in the prone position on their hands and knees, ultrasonographic measurements were obtained along the ventral surface of the abdomen. The greatest vertical depth of ascitic fluid was recorded, and the abdominal circumference was measured from this point. The ascitic fluid volume was modeled as a segment of a sphere. IDT was performed as the reference method by injecting 99mTc-labeled macroalbumin into the peritoneal cavity and determining the volume of distribution of the indicator. Nine patients were evaluated. The median volume of ascites measured by the IDT was 11.2 L (range, 1.5-17.0 L). The median volume calculated by the ultrasonographic method was 10.3 L (range, 1.2-18.0 L). The correlation coefficient between the ultrasonographic and IDT was 0.96 (P < .001). Our technique accurately determines the volume of ascites using simple ultrasonographic measurements.

Ascites↗
PubMed1996

Primed in Situ Labeling as a Fast and Sensitive Method for the Detection of Specific DNA Sequences in Chromosomes and Nuclei

Primed in situ labeling (PRINS) has become a routine technique for the microscopical staining of specific DNA sequences in cells and nuclei. For this purpose, the technique has the general advantage of being fast, simple, and sensitive. Furthermore, the reaction characteristics of the technique enable it to discriminate efficiently among closely related sequences-sometimes even when these differ by only one base. This high selectivity is obtained partly because the technique works optimally with oligonucleotide probes, which select more efficiently among closely related sequences than cloned probes do. This selectivity is further enhanced because no labeling occurs subsequent to probe binding unless the hybridized probe can function as primer for DNA synthesis, a process that is efficient only when the probe (primer) matches the target perfectly. Should this in itself provide insufficient selectivity, the involved chain elongation of the probe can be used in various ways to increase the selectivity of the staining further. These features of the technique have made it attractive for the detection of repeated DNA sequences, which now can be detected with a one-step procedure of a few minutes' duration, and make it a good candidate for the future detection of single-base variations in single-copy sequences in situ.

Journal Article↗
PubMed1996

Diagnosis of Cryptosporidium parvum in patients with severe diarrhea and AIDS.

The sensitivity of noninvasive stool microscopy and endoscopic biopsies from the upper and lower gastrointestinal tract in the diagnosis of Cryptosporidium parvum in patients with AIDS is not known. We evaluated 30 severely immunocompromised patients with AIDS and diarrhea caused by C. parvum. C. parvum was diagnosed by either stool microscopy, endoscopic biopsy, or both. Patients submitted a mean (+/-SEM) of 3.3 +/- 0.3 stool samples, each microscopically evaluated for ova and parasites. Upper and lower endoscopy were performed in all patients and endoscopic biopsies were taken throughout the gastrointestinal tract. Diarrhea had been present for a mean of 13.5 +/- 2.3 months and mean daily stool weight was 1224 +/- 127 g. Overall, individual stool samples were insensitive, as only 53% demonstrated C. parvum. When multiple stool samples were considered for each patient, 73% of subjects demonstrated C. parvum in at least one stool sample. The sensitivity of endoscopy with mucosal biopsy varied by anatomical location: stomach (11%), duodenum (53%), terminal ileum (91%), and colon (60%). The terminal ileum was significantly more likely than the duodenum to demonstrate C. parvum (P = 0.03). Thus, duodenal biopsies are much less sensitive than those from the terminal ileum in the diagnosis of C. parvum. In AIDS patients with diarrhea undergoing colonoscopy, intubation of the terminal ileum should be performed when feasible. Although individual stool samples are insensitive in detecting C. parvum, the diagnostic yield is improved by the collection of multiple samples.

AIDS-Related Opportunistic Infections↗
PubMed1996

Primed in situ labeling (PRINS). A fast method for in situ labeling of nucleic acids.

PRimed IN Situ labeling (PRINS) is a fast and sensitive alternative to fluorescence in situ hybridization (FISH) for identification of chromosome aberrations. In this article, we present the detailed protocols for detection of repeat sequences using oligonucleotides or fragments of cloned probes as primers for PRINS. We describe a multicolor PRINS procedure for simultaneous visualization of more probes in different colors on a metaphase preparation, and a PRINS-painting procedure, which combines PRINS and chromosome painting. Finally, a protocol for detection of single-copy genes is presented.

Chromosomes, Human↗
PubMed1996

Primed IN situ labelling (PRINS) as a rational procedure for identification of marker chromosomes using a panel of primers differentially tagging the human chromosomes.

PRimed IN Situ labelling (PRINS) is a highly specific and sensitive technique for detecting DNA sequences on human chromosomes in situ. PRINS is currently being introduced for research and routine analysis in clinical and cancer genetics. In this paper, we report a rational PRINS procedure for the rapid identification of marker chromosomes. Using this method it is possible to test a sample from a patient with up to eight different primers simultaneously on one slide. We have synthesized oligonucleotide primers that can differentially tag the human chromosomes, and with the protocol presented in this report we are able to identify the chromosomal origin of a marker chromosome within 2 hours.

Amniocentesis↗
PubMed1996

M-mode echocardiographic diagnosis of dilated cardiomyopathy in giant breed dogs.

M-mode echocardiograms were recorded from 62 giant breed dogs without historical, clinical, electrocardiographic and roentgenologic signs of heart disease, from six dogs with asymptomatic dilated cardiomyopathy (DCM, NYHA class I), and 13 dogs with symptomatic DCM (NYHA class III-IV). There was a general trend that several echocardiographic parameters were significantly in control Great Danes as compared to Newfoundlands and Irish Wolfhounds. There were substantial differences in left ventricular size both in systole and diastole and in systolic indices of the left ventricle between the control group, the asymptomatic dogs and symptomatic dogs with DCM (P = 0.0001). There was also a significant decreased in the interventricular septum thickness (P = 0.0001) and left ventricular free wall thickness in systole (P = 0.002) and diastole (P = 0.005) between the three groups. Furthermore, the left atrial/aortic ratio was significantly different between the three groups (P = 0.0001). It was concluded that this study established echocardiographic reference values in giant breed dogs which may be useful in the study of heart diseases in giant breed dogs.

Animals↗
PubMed1996

Clinical utility and cost effectiveness of Helicobacter pylori testing for patients with duodenal and gastric ulcers.

OBJECTIVE: current consensus guidelines recommend that all patients demonstrating either a gastric or duodenal ulcer be tested for Helicobacter pylori, the most common cause of ulcers. We determined the clinical utility and cost effectiveness of H. pylori testing in patients with duodenal and gastric ulcers. METHODS: A retrospective evaluation and cost-effectiveness analysis of 565 consecutive patients with endoscopically demonstrated gastric or duodenal ulcers over a 4-yr period in a large, urban general hospital. The main outcome variables are the percentage of patients who had a gastric biopsy, the prevalence of H. pylori, and the cost effectiveness of testing (antral biopsy, CLO test, serum antibody, and urea breath test) for H. pylori. RESULTS: Significantly more patients with endoscopically documented duodenal ulcers had an antral biopsy performed in 1993 and 1994 when compared with patients from 1991 and 1992 (p < 0.00001). For patients with gastric ulcers, biopsies were performed at a similar rate throughout this study. Overall, patients with duodenal and gastric ulcers demonstrated H. pylori 75% and 69% of the time, respectively. The total charges for biopsy documentation and treatment of H. pylori in all duodenal ulcer patients in this cohort was estimated at $25,135. If a biopsy for H. pylori had been performed in all patients the actual charges would have been $77,443. Conversely, charges would have been only $8085 had all patients been empirically treated for H. pylori based on the high pretest probability of infection. CONCLUSIONS: Routine testing for H. pylori is very expensive, regardless of the diagnostic method used. Biopsy results do not provide clinically useful information in most patients with duodenal ulcers and may be misleading if falsely negative.

Anti-Bacterial Agents↗
PubMed1996

[Acute organic psychosis after malaria tropica].

Neuropsychiatric complications in the course of plasmodium falciparum infection are usually summarized as cerebral malaria. Heterogeneous clinical symptoms, different courses and inconstant parasitemia, however, suggest different pathogenic mechanisms. We report a case of an acute symptomatic psychosis occurring two weeks after successful therapy of a primary manifestation of plasmodium falciparum infection. The diagnosis of meningoencephalitis was based on lymphocytic pleocytosis of cerebrospinal fluid and hyperintense lesions in cranial magnetic resonance imaging. Due to the lack of plasmodium falciparum parasitemia and of serological evidence of viral infection a final diagnosis was not possible. Considering the pertinent literature, an immune-mediated complication of plasmodium falciparum infection (acute disseminated encephalomyelitis, ADEM) appears to be more probable than a direct viral or plasmodium CNS infection. We propose to reverse the term cerebral malaria for the cases with direct pathogenic influence of plasmodium falciparum, and to distinguish it from cases with possible immune-mediated pathogenesis.

Adult↗
PubMed1995

Partial triplication (7q) in a child with acute lymphoblastic leukemia demonstrated with conventional cytogenetics, PRINS, and chromosome painting.

In this report we describe a partial triplication (7q) and other structural aberrations found in a child with acute lymphoblastic leukemia (ALL), and we demonstrate the importance of PRimed IN Situ labeling (PRINS) and chromosome painting as a support to banding analysis for the clarification of complex structural chromosome rearrangements. Initially, the der(7) was interpreted as der(7)t(1;7;7). However, PRINS and chromosomes painting showed that der(7) consisted entirely of chromosome 7 material. Further, a derivative chromosome interpreted by banding analysis as a der(17)t(?1;17) was shown to be der(17)t(13;17) by the newly developed PRINS painting technique.

Child↗