ABSTRACT
UNLABELLED: Aim of the study was to determine the time needed for establishing maximal labelled red blood cell concentration in hemangioma by scintigraphic semiquantitative blood pool estimation as a function of time. PATIENTS AND METHODS: Eleven patients (eight females and three males) with total number of fourteen liver hemangiomas have been examined. Nine of them had solitary lesions and remaininig two patients had two and three liver hemangiomas, respectively. All patients underwent blood pool scintigraphy 40, 60, 120 and 180 minutes after in vivo labelling of autologous red blood cells using 740 MBq of 99mTc. After correction for radioactive decay of 99mTc and back-ground correction blood pool indexes, as hemangioma/heart and liver/heart counting rate ratios, have been calculated. RESULTS: Mean blood pool indexes obtained 40-180 minutes after in vivo red blood cell labelling did not differ significantly (p > 0.05) neither in hemangioma (0.84-0.86) nor in liver tissue (0.55-0.58). In every acquisition time hemangioma blood pool index was substantialy higher than that of liver tissue (p < 0.01). CONCLUSION: The results of the study indicates that labelled red blood cells concentration reaches its plateau before 40th minute following in vivo labelling. The concentration difference between hemangioma and liver tissue also does not differ significantly after 40th minute of blood pool examination. In most patients blood pool scintigrams taken 60, 120 and 180 minutes following in vivo RBC labelling do not contribute to diagnostic value of the method.
Subject(s)
Erythrocytes , Hemangioma/diagnostic imaging , Liver Neoplasms/diagnostic imaging , Liver/diagnostic imaging , Technetium , Female , Hemangioma/blood , Humans , Isotope Labeling , Liver Neoplasms/blood , Male , Radionuclide ImagingABSTRACT
The repair of double strand breaks after gamma-irradiation in wild-type Escherichia coli lysogenic for lambda cI857 red3 is more efficient when lambda Gam protein is present. This phenomenon, called gam dependent radioresistance, requires the interaction of RecBCD enzyme and Gam protein. We compared cell survival after gamma-irradiation in wild-type and mutant lysogens with and without induction of Gam by transient heat treatment of the cells (6 min, 42 degrees C). The main conclusions are: (1) the RecBCD-Gam pathway of recombination repair is similar but not equivalent to RecBCD, a pathway operating in recD mutants; (2) the RecBCD-Gam pathway is dependent on recJ, recQ and recN gene products and it is proposed that the RecBCD-Gam complex has ability to load RecA protein onto single strand DNA.
Subject(s)
DNA Repair , DNA Restriction Enzymes , Escherichia coli Proteins , Escherichia coli/genetics , Exodeoxyribonucleases/genetics , Viral Proteins/genetics , Adenosine Triphosphatases/genetics , Bacterial Proteins/genetics , DNA Helicases/genetics , DNA, Bacterial , DNA-Binding Proteins , Deoxyribonucleases/genetics , Escherichia coli/enzymology , Escherichia coli/radiation effects , Exodeoxyribonuclease V , Gamma Rays , Mutation , Protein Binding , RecQ Helicases , Recombination, GeneticABSTRACT
Hepatic radionuclide angiography (HRA) is a recognised method of investigation of liver blood flow disorders caused by: diffuse and focal diseases of liver parenchyma or disorders of blood flow in extrahepatic liver vessels. Hepatic perfusion index (HPI) based on Sarper's slope method is significantly lower in patients with e.g. liver cirrhosis, malignant primary and metastatic liver diseases and portal vene thrombosis, but not in patients with benign focal liver leasions. Determined in liver as a whole, HPI is a sensitive indicator of the presence of malignant liver tumours, but is within normal range in patients with hepatic hemangioma. The aim of the study was to investigate characteristic of blood flow in hemangioma itself, separately from but in relation to the liver blood flow, using hepatic radionuclide angiography. We have examined 12 patients with liver hemangioma confirmed mainly by positive 99mTc-labeled red blood cell scintigraphy, which diagnostic specificity for liver hemangiomas is near 100%. 8/12 hemangiomas resulted in photopenic areas on angioscintigrams, indicating lower blood flow, and rest were isoactive to surrounding liver tissue. Regions of interest have been delineated around the photopenic areas (hemangiomas) and surrounding liver tissue. Time-activity curves have been generated and slope of the fitted hepatic artery and (portal) venous portions of the hemangioma and liver curves have been determined. Perfusion indexes of hemangioma (PIH) and liver (HPI) have been calculated from the slopes, expressing portal venous flow as a portion of entire blood flow to the region. In addition, times of arrival and transit of intravenous bolus of 99mTc-pertechnetate through the hemangioma and liver tissue have also been derived from time-activity curves. Slope of the venous portion of the hemangioma time-activity curve is significantly lower then that of the venous portion of the liver curve (p < 0.01). So that, perfusion index of hemangioma (PIH = 0.34 +/- 0.12 (mean +/- SD) is significantly lower then hepatic perfusion index (HPI = 0.57 +/- 0.08) (p < 0.05). Bearing in mind interference of superimposed liver activity with that of hemangioma, these results indicate that liver hemangiomas are dominantly if not exclusively irrigated by hepatic artery branches. There are no data regarding relation between arterial and venous blood flow in liver hemangiomas determined by HRA. Obtained results are in harmony with arteriography data which confirm slow arterial blood flow through hemangiomas. Portal venous inflow of some angiomatous liver lesions in infants and children, and arterio-portal shunting in hemangiomas have been rarely reported. Results of this study indicate that regional determination of perfusion index and other HRA parameters in patients with focal liver lesion enables differentiation between tissues with different intensity and pattern of blood flow. The method could be used in examination of vascularisation pattern of other focal liver lesions.
Subject(s)
Erythrocytes , Hemangioma/blood supply , Liver Neoplasms/blood supply , Radiopharmaceuticals , Sodium Pertechnetate Tc 99m , Hepatic Artery/diagnostic imaging , Hepatic Veins/diagnostic imaging , Humans , Radionuclide ImagingABSTRACT
In vitro, RecB1-929, the truncated Escherichia coli RecB polypeptide, comprising the N-terminal (helicase) domain of RecB, can combine with RecC and RecD subunits of RecBCD enzyme. The resulting RecB1-929CD heterotrimer is a potent helicase; due to the loss of the nuclease center of RecB, it is devoid of DNase activities. By making use of the RecB1-929-producing plasmid pMY100, the in vivo behavior of this truncated polypeptide was studied. The following observations were made. (i) Large amounts of RecB1-929 in the pulse-heated lambdacI857gam+ lysogens prevented the growth of a gene 2 mutant of bacteriophage T4. It may be inferred that lambda-Gam protein, which otherwise inhibits RecBCD DNase and thus permits the growth of this phage, is bound by the helicase domain of RecB. (ii) The simultaneous presence of RecB1-929, RecC, and RecD did not restore recombination proficiency and ultraviolet resistance of recB cells. (iii) The presence of RecB1-929 did not alter recombination and repair processes in wild-type (recBCD+) cells. Even excessively large amounts of this truncated polypeptide did not reduce degradation of chromosomal DNA damaged by y-rays. It may be inferred that under in vivo conditions, the 30-kDa domain of RecB is essential for assembly of the RecBCD enzyme and/or for holding its three subunits together.
Subject(s)
Escherichia coli Proteins , Escherichia coli/enzymology , Exodeoxyribonucleases/metabolism , Bacteriophage lambda/genetics , Bacteriophage lambda/physiology , DNA Repair , Escherichia coli/genetics , Escherichia coli/radiation effects , Escherichia coli/virology , Exodeoxyribonuclease V , Gamma Rays , Recombination, Genetic , Ultraviolet Rays , Viral Proteins/metabolismABSTRACT
BACKGROUND: The aim of the study is to evaluate gallbladder (GB) motor function, by infusion cholescintigraphy, in patients after total gastrectomy (Roux-en-Y) with expected disturbances in the physiological regulation of biliary tract motility. METHODS: The study was done in 10 controls, as well as in 12 patients early (less than 2 months) and in 14 late (6 months-2 years) after surgery. Anterior abdominal imaging by gamma camera and computer acquisition was performed during three-hours infusion of 150 MBq, preceded by the loading dose of 50 MBq of 99mTc-EHIDA in bolus injection. The test meal stimulation was done in the 120th min of the study. GB TA curve was obtained and five parameters of GB motility were analysed: durations of filling (ascending) and emptying (descending) phases, filling and emptying rate ratio and ejection fraction and rate. RESULTS: Our results have shown that in the early period after the operation GB filling is prolonged and emptying impaired, while after several months GB motor function is normalised. CONCLUSIONS: It can be concluded that the infusion cholescintigraphy is potentially useful in patients after such surgery to decide on the specific treatment introduction in order to prevent GB calculosis and other complications.
ABSTRACT
Endometrial carcinoma, the fourth most common cancer in women, is primarily a disease afflicting postmenopausal women and usually presents with vaginal bleeding or vaginal discharge. A slender, athletic 44-year-old woman was diagnosed with endometrial carcinoma after presenting with an isolated, solitary femoral bone metastasis. She had no symptoms except for progressive left knee pain. An open biopsy of the lesion in the proximal left femur revealed metastatic adenocarcinoma compatible with an endometrial primary. An endometrial biopsy subsequently revealed moderately differentiated endometrioid adenocarcinoma. The patient underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy, and adjuvant chemotherapy. An aggressive metastatic workup revealed no other sites of metastatic disease. The femoral metastasis was treated with radiation. On chronic progestin therapy, the patient is clinically free of disease 2 years following diagnosis. Patients with endometrial carcinoma (with otherwise early stage disease) who present with an isolated skeletal lesion may represent an unusual group with perhaps a better prognosis. This patient received aggressive multi-disciplinary therapy and has had a two year progression-free interval.
Subject(s)
Adenocarcinoma/pathology , Bone Neoplasms/secondary , Endometrial Neoplasms/pathology , Adult , Female , Femur , HumansABSTRACT
Estimation of the gallbladder (GB) motility disorders after gastric surgery has not yet been assessed because of the shortage of the reliable diagnostic methods. The aim of the study is introduction, modification and establishment of the infusion cholescintigraphy into clinical practice and its performance in the groups of patients with gastric resection (RVBI i RVBII), total gastrectomy and patients after gastroplasty. Obtained data produced information about motility disorders caused by billateral truncal vagotomy, lack of the food transit through duodenum and if the motility disorders are the same in different time periods after operation. In groups of patients without truncal vagotomy (RVBI and RVBII), minor motility disorders are registered in comparison to the groups after truncal vagotomy. In the period of 6 months after surgery, higher motility disorders are registered in the group of patients with total gastrectomy, while after 9-12 months GB motility completely recovers. Groups with preserved transit of food through duodenum (RVBI and gastroplasty), has minor motility disorders in comparison to the group without transit of food through duodenum (RVBII and total gastrectomy). By introducing infusion cholescintigraphy, reliable method for the GB motility assessment is obtained.
Subject(s)
Duodenum/surgery , Gallbladder/diagnostic imaging , Stomach/surgery , Adult , Aged , Female , Gallbladder/physiopathology , Gallbladder Emptying , Humans , Male , Middle Aged , Postoperative Complications , Radionuclide ImagingABSTRACT
To ascertain whether gastric emptying of solids is affected by visceral autonomic neuropathy, 30 noninsulin-dependent diabetics (10 with autonomic neuropathy, 10 with peripheral and 10 without neuropathy) and 10 control subjects were studied. Subjects were screened by clonidine test and two parasympathetic tests of cardiovascular reflexes to identify the presence of autonomic neuropathy. The peripheral neuropathy was diagnosed by classic neurological examination and EMG. Delayed gastric emptying was assessed by dynamic scintigraphy, using 99mTc labeled ham and eggs. The gastric emptying of solids was markedly delayed in diabetics, particularly in diabetics with poor metabolic control (p < 0.01) and those with autonomic and peripheral diabetic neuropathy (p < 0.05). The results of our study suggest that dynamic scintigraphy may be a more sensitive method than other tests for autonomic dysfunction of the gut in diabetics with the early manifestation of diabetic gastroparesis.
Subject(s)
Autonomic Nervous System Diseases/complications , Diabetes Mellitus, Type 2/diagnostic imaging , Diabetic Neuropathies/complications , Gastric Emptying , Autonomic Nervous System Diseases/diagnosis , Diabetes Mellitus, Type 2/complications , Diabetes Mellitus, Type 2/physiopathology , Diabetic Neuropathies/diagnosis , Female , Humans , Male , Middle Aged , Radionuclide Imaging , Stomach/diagnostic imagingABSTRACT
We report a 60-year-old man with intermittent diarrhea for 15 years which was worsened by cholecystectomy. The results of routine laboratory tests, x-ray studies of the gut, and endoscopy were normal. Fecal fat excretion was normal, but total bile acid excretion was increased in the alkaline feces. The retention of 75SeHCAT was low. Jejunal mucosal biopsy showed normal mucosa. Ileal biopsy was performed at ileoscopy some 10 to 15 cm proximal to the ileocecal valve. Scanning-electron and light microscopy showed a transitional zone between villous atrophy in the distal and normal mucosa in the proximal part of the biopsy specimen. The response of diarrhea to cholestyramine treatment was unequivocal, suggesting bile acid malabsorption. The increased enterohepatic cycling of bile acids after cholecystectomy may be responsible for a decrease in their ileal uptake. Very often, as in our patient, the diarrhea precedes cholecystectomy and is considerably increased by it. Cholecystectomy may unmask a previously unrecognized bile acid transport defect. In our patient, this defect might have been caused by the villous atrophy of the terminal ileum.
Subject(s)
Bile Acids and Salts/metabolism , Cholecystectomy/adverse effects , Diarrhea/etiology , Ileal Diseases/metabolism , Malabsorption Syndromes/complications , Cholestyramine Resin/therapeutic use , Chronic Disease , Diarrhea/drug therapy , Feces/chemistry , Humans , Ileal Diseases/complications , Ileal Diseases/diagnosis , Intestinal Mucosa/pathology , Malabsorption Syndromes/diagnosis , Malabsorption Syndromes/drug therapy , Male , Middle Aged , Selenium Radioisotopes , Taurocholic Acid/analogs & derivativesABSTRACT
The study presents preliminary results and suggests the role of scintigraphy of synthetic vascular prosthesis by 99mTc-HMPAO labelled leukocytes for detection of graft infections. Analysis of the results obtained revealed true positive in 6, true negative in 3 and suspicious findings in 3 patients (in one of them the suspicious was confirmed on reoperation). False positive and false negative results were not obtained. Early and accurate diagnosis of occult infection of the synthetic vascular graft is of utmost importance for the prompt starting of the therapy. Due to its high sensitivity and specificity, 99mTc-HMPAO-leukocytes scintigraphy is a very useful method for the detection of graft infections.
Subject(s)
Blood Vessel Prosthesis/adverse effects , Leukocytes , Organotechnetium Compounds , Oximes , Prosthesis-Related Infections/diagnostic imaging , False Negative Reactions , False Positive Reactions , Humans , Leg/blood supply , Radionuclide Imaging , Technetium Tc 99m ExametazimeABSTRACT
The aim of this study is the assessment of the gallbladder (GB) motility in the controls without (C) and with (Cs) test-meal stimulation, as well as in the patients early (EPG) and late (LPG) after total gastrectomy. Data were collected with ROTA scintillation camera, during (3 h, 10 ml/h) infusion of 150 MBq, 0.25 mg/ml 99mTc-EHIDA, preceded by a loading dose (0.5 mg/ml, 50 MBq). While in EPG, GB motility is impaired, it achieves physiological values in LPG patients, which can be attributed to establishment of corresponding hormonal mechanisms, in the late postoperative period.
Subject(s)
Gallbladder Emptying , Gallbladder/diagnostic imaging , Gastrectomy , Eating , Gastrectomy/adverse effects , Humans , Imino Acids , Organotechnetium Compounds , Radionuclide Imaging , Technetium Tc 99m Diethyl-iminodiacetic AcidABSTRACT
The aim of the study is to demonstrate general function of the cholecyst through selected quantitative parameters derived from the quantitative radionuclide cholecystography method, using our own computer software HIDATA, and to evaluate values of specific quantitative parameters in 15 patients presenting with chronic calculous and 15 with chronic acalculous cholecystitis. A control group comprised 10 subjects with no changes on the cholecyst. Of four quantitative parameters calculated during cholecyst filling, the only significant one was the ascending segment slope of the curve from specific ROI, that is, K1 derived from it, because it shows its functional status, depending on the changes in its wall and the lumen content. The most significant parameters which maintain motor function of the cholecyst are ejection fraction (EF) and ejection rate (ER) which are always decreased in chronic cholecystitis, regardless of the presence of calculosis and the number of calculi in the lumen. The ejection fraction is especially decreased in the multiple sclerosis group; it is significantly decreased when compared with acalculous chronic cholecystitis. Our results indicate that a selection of parameters used in clinical practice for the assessment of the cholecyst function is necessary. Our program HIDATA included a large number of parameters of which three were classified as important for the assessment of the cholecyst function (K1, EF, ER), reflecting the process of filling and emptying of the cholecyst and offering reliable and valuable data for the treatment.
Subject(s)
Gallbladder/diagnostic imaging , Gallbladder/physiopathology , Image Interpretation, Computer-Assisted , Cholecystitis/diagnostic imaging , Cholecystitis/physiopathology , Cholelithiasis/diagnostic imaging , Cholelithiasis/physiopathology , Humans , Image Processing, Computer-Assisted , Radionuclide ImagingABSTRACT
A simplified and efficient procedure for 99mTc-HMPAO-labelling of leukocytes is described. For this purpose, the pH and concentration of the 99mTc-HMPAO preparation was modified. Leukocytes were isolated from a 20 mL mixture of patient blood, 5 mL ACD and 0.8 mL methylcellulose after 1 h sedimentation of erythrocytes and centrifugation (at 400 g) of the obtained plasma layer. Simultaneously, 99mTc-HMPAO was prepared (one single-dose kit for two patients) by adding 2.2 mL 99mTc-generator eluate and, after 10 min, 0.3 mL of phosphate buffer to lower the pH to 7. The isolated WBCs were then labelled by the addition of 1-1.2 mL of 99mTc-HMPAO solution and incubated for 20 min. The unbound tracer was then discarded, the labelled WBC washed and finally resuspended in autologous cell-free plasma. Leukocytes labelled by this procedure were used for scintigraphic localization of inflammatory lesions and abscesses in the gastro-intestinal tract. The labelling efficiency was 60 +/- 9%, with a separation yield of 55 +/- 11%.
Subject(s)
Abscess/diagnostic imaging , Inflammation/diagnostic imaging , Leukocytes/metabolism , Organotechnetium Compounds , Oximes , Abscess/blood , Humans , Hydrogen-Ion Concentration , Inflammation/blood , Leukocytes/physiology , Radionuclide Imaging , Technetium Tc 99m Exametazime , Time FactorsABSTRACT
We investigated DNA metabolism in Escherichia coli cells carrying the multicopy recD+ plasmid (pKI13). In the presence of pKI13, the cellular level of the recD gene product (RecD polypeptide) is amplified at least 60-fold. Overproduction of the RecD polypeptide has no effect on UV repair and conjugational recombination. In contrast, high cellular levels of this polypeptide sensitize wild-type cells to gamma-radiation; also, they increase the rate of radiation-induced DNA degradation. A possible mechanism for the enhancement of gamma-ray-induced killing by large amounts of the RecD polypeptide is discussed.
Subject(s)
DNA Repair/genetics , Escherichia coli Proteins , Escherichia coli/radiation effects , Exodeoxyribonucleases/genetics , DNA, Bacterial/metabolism , Dose-Response Relationship, Radiation , Escherichia coli/genetics , Exodeoxyribonuclease V , Gamma Rays , Gene Expression/genetics , Kinetics , Plasmids/genetics , Recombination, Genetic/genetics , Ultraviolet RaysABSTRACT
Idiopathic thrombocytopenic purpura is an autoimmune disease in which macrophages of reticuloendothelial system, mainly in the spleen, remove platelets covered by autoantibodies from circulation. By removing the spleen 60-80% of patients are cured. Partial remission is achieved in 10-20% of cases. Recurrence of idiopathic thrombocytopenic purpura in a splenectomized patient achieving complete remission, may be caused by hypertrophy of one or more of the retained accessory spleens. We describe a 41-year-old wonam in whom splenectomy for idiopathic thrombocytopenic purpura was performed 10 years ago. After quick and full remission which lasted almost 10 years, a full reccurrence of the disease with severe thrombocytopenia and haemorhagic syndrome appeared. With ultrasonography, computed tomography and scintigraphy accessory spleens in the splenic fossa were found. Removal of 3 accessory spleens, 21 gram of weight, led to quick and full remission of the disease. A number of platelets stayed over 200 x 10(9)/l with no additional treatment.
Subject(s)
Purpura, Thrombocytopenic, Idiopathic/etiology , Spleen/abnormalities , Adult , Female , Humans , Purpura, Thrombocytopenic, Idiopathic/surgery , Recurrence , SplenectomyABSTRACT
The DNA of a gene 2 mutant (T4 2-) of phage T4 is degraded by RecBCD enzyme in the bacterial cytoplasm. Under normal conditions, recBCD+ cells are therefore incapable of supporting the growth of phage T4 2-. Only if the nucleolytic activity of RecBCD enzyme is absent from the cytoplasm are T4 2(-)-infected bacteria able to form plaques. We found that recBCD+ cells can form plaques if, before infection with T4 2-, they have been exposed to gamma radiation. It is suggested that gamma ray-induced lesions of the bacterial DNA (e.g., double-strand breaks) bind RecBCD enzyme. This binding enables the enzyme to begin to degrade the bacterial chromosome, but simultaneously prevents its degradative action on the ends of minor DNA species, such as unprotected infecting phage chromosomes. Degradation of the chromosomal DNA, which occurs during the early postirradiation period, ceases about 60 min after gamma ray exposure. The reappearance of the nucleolytic action of RecBCD enzyme on T4 2- DNA accompanies the cessation of degradation of bacterial DNA. Both, this cessation and the reappearance of the nucleolytic action of ReCBCD enzyme on T4 2- DNA depend on a functional recA gene product. These results suggest that postirradiation DNA degradation is controlled by the recA-dependent removal of RecBCD enzyme from the damaged chromosome. By making use of the temperature-sensitive mutant recB270, we showed that RecBCD-mediated repair of gamma ray-induced lesions occurs during the early postirradiation period, i.e. during postirradiation DNA degradation. It is shown that the RecD subunit of RecBCD enzyme also participates in this repair.
Subject(s)
DNA Damage , DNA Helicases/physiology , DNA Repair , Escherichia coli Proteins , Exodeoxyribonucleases/physiology , Gamma Rays/adverse effects , Cell Survival/radiation effects , DNA/metabolism , DNA/radiation effects , Dose-Response Relationship, Radiation , Escherichia coli/radiation effects , Exodeoxyribonuclease V , Genes, Bacterial , Protein Binding , T-Phages/pathogenicity , Time FactorsABSTRACT
The mechanism of DNA replication in ultraviolet (UV)-irradiated Escherichia coli is proposed. Immediately after UV exposure, the replisome aided by single-strand DNA-binding protein (SSB) can proceed past UV-induced pyrimidine dimers without insertion of nucleotides. Polymerisation eventually resumes somewhere downstream of the dimer sites. Due to the limited supply of SSB, only a few dimers can be bypassed in this way. Nevertheless, this early DNA synthesis is of great biological importance because it generates single-stranded DNA regions. Single-stranded DNA can bind and activate RecA protein, thus leading to induction of the SOS response. During the SOS response, the cellular level of RecA protein increases dramatically. Due to the simultaneous increase in the concentration of ATP, RecA protein achieves the high-affinity state for single-stranded DNA. Therefore it is able to displace DNA-bound SSB. The cycling of SSB on and off DNA enables the replisome to bypass a large number of dimers at late post-UV times. During this late replication, the stoichiometric amounts of RecA protein needed for recombination are involved in the process of postreplication repair.
Subject(s)
DNA Replication/radiation effects , DNA, Bacterial/biosynthesis , DNA, Single-Stranded/biosynthesis , Rec A Recombinases/genetics , DNA, Bacterial/radiation effects , DNA, Single-Stranded/radiation effects , Rec A Recombinases/biosynthesis , Rec A Recombinases/radiation effects , Ultraviolet RaysABSTRACT
The recB21 mutation abolishes the exonuclease activity of the RecBCD enzyme (exonuclease V) of Escherichia coli. This might be due to the polar effect of recB21 on expression of the recD gene, the product of which is an essential component of the RecBCD enzyme. To achieve synthesis of the recD gene product, the recD+ plasmid was introduced into the recB21 mutant. Degradation of the endogenous DNA damaged by gamma-rays and degradation of the DNA of a phage T4 gene 2 mutant were nevertheless abnormally small in this strain. Thus, the functional recB gene product is required for the degradative function of the RecBCD enzyme.
Subject(s)
DNA Repair , DNA, Bacterial/metabolism , Escherichia coli Proteins , Escherichia coli/enzymology , Exodeoxyribonucleases/physiology , Exodeoxyribonuclease V , Structure-Activity RelationshipABSTRACT
Post-ultraviolet DNA synthesis kinetics were investigated in the Escherichia coli uvrA recA strain and its isogenic counterpart, overproducing single-strand DNA-binding protein (SSB). It was demonstrated that large quantities of SSB enhance the capacity of the unmodified replisome to use the UV-damaged template for DNA synthesis. DNA thus synthesized is of low molecular weight, as shown by sedimentation in alkaline sucrose gradients. It is therefore suggested that SSB actively participates in the replisome translocation past dimers and/or the initiation of new DNA chains downstream of these lesions.
Subject(s)
DNA Repair , DNA, Bacterial/biosynthesis , DNA-Binding Proteins/physiology , Escherichia coli/radiation effects , Ultraviolet RaysABSTRACT
Three patients are presented with a history of chronic watery diarrhea due to bile acid malabsorption, proved by the tauro-23[75Se]selena-25 homocholic acid test and an unequivocal response to cholestyramine therapy. Fecal fat tests, Schilling tests, and barium studies of the small intestine and colon were all normal. Jejunal biopsies were normal but multiple biopsies of the terminal ileum, performed by retrograde ileoscopy, showed uniform crypt hyperplastic villous atrophy and features of colonic metaplasia with increased mononuclear infiltration of the lamina propria. All 3 patients demonstrated evidence of abnormal immune function, including the presence of serum autoantibodies, circulating immune complexes, and hypocomplementemia. One patient had Sjögren's syndrome. This disorder, which might be immunologically mediated, should be called primary bile acid malabsorption and should be distinguished from other ileal disorders.