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Biomedical subjects

D M Jensen

Publications and source records attributed to D M Jensen.

At least 109 records · Page 6Linked to original sources
PubMed1982

Chronic liver disease manifesting as Waldenström's macroglobulinemia.

A 59-year-old woman was initially seen with anemia, purpura, gastrointestinal tract and vaginal bleeding, pronounced hyperglobulinemia, and an increased serum viscosity, all suggestive of Waldenström's macroglobulinemia. Subsequent investigation, however, indicated that these abnormalities were more likely due to chronic active hepatitis with cirrhosis. The striking similarity of this patient's symptoms to those of Waldenström's macroglobulinemia and the pathophysiologic characteristics of polyclonal hypergammaglobulinemia in chronic liver disease are discussed.

Antigens↗
PubMed1982

Acute hepatitis B: a further serological characterization.

Sequential determinations of HBsAg, anti-HBs, HBeAg, anti-HBe, and anti-HBc in thirteen patients with acute hepatitis B have shown that the viral antigens and their respective antibodies may be simultaneously absent (9/13 with serologic window) or present (6/13 with presumed immune complex formation) in the early convalescent period. These data emphasize the usefulness of sequential determinations of antigen and antibody in the unequivocal assessment of etiology and potential for chronicity and contagion) in resolving acute hepatitis B. The transient appearance of an antibody to liver specific protein (anti-LSP) in eleven out of thirteen patients was documented; we found no correlation of anti-LSP titers with viral antigens or host antibody titers.

Acute Disease↗
PubMed1982

Comparison of argon laser photocoagulation and bipolar electrocoagulation for endoscopic hemostasis in the canine colon.

Severe bleeding from the lower gastrointestinal tract commonly occurs from mucosal lesions such as angiodysplasia and less often from acute ulcerations. Endoscopic coagulation of such lesions is now feasible. Our purpose was to compare the efficacy and histologic injury of bipolar electrocoagulation and argon laser photocoagulation applied at laparotomy in the canine colon. After right colotomy and heparinization in adult mongrel dogs, bleeding standard ulcers were randomly assigned to treatment or control. The colonic ulcers randomized to each group were not significantly different in size or bleeding rate. Efficacy of treatment was evaluated acutely. Adjacent normal mucosa was treated with the same modality as the ulcer to simulate treatment of a mucosal lesion. The same total exposure time (argon laser photocoagulation) or number of pulses (bipolar electrocoagulation) was used for these paired treatments. Gross and histologic injury were determined after 7 days. Both argon laser photocoagulation and bipolar electrocoagulation were uniformly effective in controlling bleeding from standard colonic ulcers and the incidence of full thickness injury was similar, 33%-48%. The histologic damage seen with normal mucosa treatment was consistently less than with standard ulcers for all treatment groups. The difference is easily explained by the reduction in colonic wall thickness of about 50% with creation of standard ulcers. In our opinion, argon laser photocoagulation and bipolar electrocoagulation are safe enough to be used in clinical trials for control of colonic bleeding from mucosal lesions but not acute colonic ulcers.

Animals↗
PubMed1982

Comparison of endoscopic electrocoagulation and laser photocoagulation of bleeding canine gastric ulcers.

The most promising endoscopic hemostatic techniques all depend upon heat to coagulate. Four thermally active techniques under similar controlled conditions in this endoscopic study were compared. The study was undertaken to compare the efficacy and histologic damage of monopolar electrocoagulation (MPEC), bipolar electrocoagulation (BPEC), argon laser photocoagulation (ALP) and neodymium-yytrium-aluminum-garnet (YAG) laser photocoagulation applied endoscopically to control bleeding from standard canine gastric ulcers. An open-closed model utilizing a nontraumatic intestinal clamp in heparinized adult mongrel dogs was used. Bleeding ulcers were randomly assigned to an endoscopic treatment modality or control. The endoscopic techniques and parameters of treatment for this study were established from a previous experience with each modality and from endoscopic treatment in pilot studies. Quantitative efficacy and subjective ease of endoscopic treatment were evaluated acutely; gross and histologic injury were determined after 7 days. Our conclusions were that more energy or greater power was required with each method to treat bleeding standard ulcers efficiently through the endoscope than at laparotomy. It was also concluded that each method was 93% or more effective in halting bleeding in this canine ulcer model but there were differences in ease of endoscopic use. Both lasers were much easier to apply than electrocoagulation. The order of decreasing ease of application was YAG, ALP, MPEC, BPEC. Argon laser and BPEC caused significantly less tissue injury than either MPEC or YAG. The order of increasing injury or decreasing margin of safety was ALP, BPEC, YAG and MPEC. In contrast to electrocoagulation, especially monopolar, laser related tissue injury was generally predictable and correlated with total treatment energy, animal weight or gastric overdistension, or both. The limitations, advantages, and disadvantages of each hemostatic technique are discussed and compared.

Animals↗
PubMed1981

Laparoscopy: advances in biopsy and recording techniques.

We have developed a second puncture accessory set and photographic technique for laparoscopy which are easy to use and potentially safer than others commonly used. A smaller second trocar (4mm) with various biopsy accessories, suction-coagulation cannula, and insulated grasper has been developed and successfully used in a series of more than 400 high risk patients where tissue samples were obtained under local anesthesia without serious complications or fatalities. The smaller size facilitated easy and safe introduction and manipulation. For laparoscopic photography a presterilized quartz rod attached to a sealed flash tube is used which is synchronized with a flash generator and 35-mm camera. An accessory trocar and the quartz rod are introduced under visual guidance parallel to the examining trocar. A separate "modeling" light is incorporated to provide illumination for observation. This photographic technique provides excellent illumination through a smaller trocar and probe than previously reported.

Biopsy↗
PubMed1981

Peptic ulcer: new therapies, new diseases.

Although hospitalizations and deaths attributable to peptic ulcer have decreased notably during the past decade, it is not certain whether this decrease is because of reduced incidence of new cases or changes in other factors, such as the severity of the disease. Several genetic traits associated with peptic ulcer have been recognized. Hyperpepsinogenemia I is the most prevalent. Peptic ulcer is a heterogeneous group of disorders with multiple genetic and environmental causes. One manifestation of the diversity of ulcer disease is the variety of physiologic abnormalities seen in patients. The use of endoscopy has enabled more reliable evaluation of new treatments. Histamine H2-receptor antagonists are the dominant mode of treatment, but increasing attention is being given to agents that enhance the resistance of the mucosa to injury, such as prostaglandins. Because of the lower frequency of side effects, proximal gastric vagotomy is gradually replacing truncal vagotomy with drainage. The possibility that endoscopic treatments, such as laser coagulation, may reduce mortality from bleeding ulcers is being investigated.

Duodenal Ulcer↗
PubMed1981

Computer-assisted electrocoagulation: bipolar vs. monopolar in the treatment of experimental canine gastric ulcer bleeding.

A prospective, randomized, controlled experiment using a canine model of severely bleeding gastric ulcer was performed to compare the hemostatic efficacy and tissue damage produced by one bipolar and two monopolar electrodes. Both monopolar electrodes were insulated to their tips; they differed with respect to their surface area (3 mm2 vs. 4 mm2). The force of electrode application was controlled. An analog computer monitored the energy per electrode application and predetermined the duration of each application. Fifty-nine standard acute bleeding ulcers were made and treated one at a time in six heparinized foxhounds at sterile laparotomy. Treatment was randomized to the bipolar or to one of the monopolar electrodes within each of three bleeding strata. No significant difference was observed in hemostatic efficacy among the three electrodes. Treated ulcers were examined histologically after 5 to 7 days to determine the maximum tissue damage produced: Bipolar electrocoagulation caused significantly less damage than electrocoagulation with either monopolar electrode. We conclude that with these electrodes, bipolar electrocoagulation is equally effective for stopping bleeding but results in less tissue injury than monopolar electrocoagulation in this experimental model.

Animals↗
PubMed1980

YAG laser treatment of experimental bleeding canine gastric ulcers.

The neodymium-YAG laser was used to treat bleeding experimental canine gastric ulcers in four separate studies: (a) Extensive investigation by using the 1.06 micron YAG laser wavelength was performed to determine optimal YAG laser treatment parameters to maximize hemostatic efficacy while minimizing associated tissue injury. Eight out of 43 combinations of power, pulse duration, and spot size, with and without coaxial CO2 were found to be best. The range of settings tested were 30-90 W for power; 0.2-1 sec pulse duration; and 2.0- and 3.4-mm spot sizes, with and without coaxial CO2. (b) Five of these treatment combinations were studied in more detail to assess the respective effect of spot size, pulse duration, and presence or absence of coaxial CO2 on tissue injury. In spite of optimizing treatment parameters and conditions, each combination caused significant damage to the gastric wall. No acute perforations occurred. (c) Endoscopic YAG laser treatments were applied successfully. Efficacy and total energy requirements were compared with similar treatments previously done at laparotomy. (d) In an attempt to reduce tissue damage, the YAG laser was modified to produce a 1.3-microm wavelength. YAG laser treatment using this alternative wavelength caused more immediate damage than the 1.06 micron wavelength. From these studies we conclude: (a) YAG laser photocoagulation effectively stopped experimental gastric ulcer bleeding when applied both at laparotomy and endoscopy; (b) compared to untreated ulcers, YAG laser treatment caused significant tissue damage despite control of several important variables (power output, spot size, pulse duration, and coaxial CO2); (c) increased total energy, larger spot size, and longer pulse duration appeared related to increased tissue injury with YAG laser treatment; total energy was the single most important factor. (d) Successful hemostasis with endoscopic application of the YAG laser required more total energy than treatment of laparotomy. (e) Modification of the YAG laser wavelength to 1.3 microns did not reduce tissue injury.

Acute Disease↗
PubMed1978

Detection of antibodies directed against a liver-specific membrane lipoprotein in patients with acute and chronic active hepatitis.

A specific and sensitive radioimmunoassay was used to measure the levels of antibody to a liver-specific membrane lipoprotein in patients with acute and chronic liver disease. Antibody was detected in 29 of 30 patients with chronic active hepatitis (all of 15 HBsAg-negative and 14 of 15 HBsAg-positive cases), and in 10 of 17 patients with chronic persistent hepatitis but at significantly lower titer. The titer of antibody to the lipoprotein showed a significant correlation with activity of disease as judged histologically and biochemically. Transiently elevated levels were found in 20 of 21 patients with acute viral hepatitis, but there was no correlation with the degree of liver damage. Antibody to liver-specific membrane protein may be part of the final common pathway of liver-cell damage in both HBsAg-positive and HBsAg-negative chronic activite hepatitis, whereas other immune mechanisms determine the liver-cell injury in acute viral hepatitis.

Adult↗
PubMed1978

Failure of atropine to inhibit gastrin-17 stimulation of the lower esophageal sphincter in man.

Heptadecapeptide gastrin I (G-17) contrast the lower esophageal sphincter (LES) in man and animals. Previous studies in man found that atropine infusion (12 microgram kg-1hr-1) inhibited the effect of gastrin on the LES, suggesting that this effect of gastrin is mediated by a cholinergic mechanism. Studies in the opossum have not shown similar inhibition. To reevaluate the interaction of atropine and G-17 on the LES, 5 normal males were studied. Submaximal and maximal effective doses of G-17 were used with both atropine infusion (12 microgram kg-1hr-1) and rapid intravenous injection (1 mg). There was a small decrease in basal LES pressure with atropine infusion. However, neither atropine infusion nor rapid intravenous injection inhibited LES stimulation by submaximal and maximal doses of G-17. The results do not support the hypothesis that LES responses to gastrin are mediated by an atropine-sensitive cholinergic mechanism.

Adult↗
PubMedDate not supplied

Endoscopic demonstration that vasopressin but not propranolol produces gastric mucosal ischemia in dogs with portal hypertension.

Endoscopic reflectance spectrophotometry was used to compare the effect of vasopressin and propranolol on gastric mucosal hemodynamics in dogs with surgically induced esophageal varices and prehepatic portal hypertension. Reflectance spectrophotometry provides indices of mucosal hemoglobin concentration (IHB) and oxygen saturation (ISO2). Hyperemia (increased IHB, normal ISO2), ischemia without congestion (decreased IHB, decreased ISO2), and ischemia with congestion (increased IHB, decreased ISO2) are accompanied by characteristic patterns of IHB and ISO2. Under anesthesia, measurements were obtained on separate days from the gastric corpus mucosa of eight dogs before and 2 to 10 min after either 1 to 5 units of intravenous vasopressin or 1 mg of propranolol. Results revealed that vasopressin (in doses that significantly reduced variceal and portal venous pressure in this animal model) produced a reduction in both IHB and ISO2, indicating gastric mucosal ischemia secondary to splanchnic vasoconstriction. On the other hand, propranolol in a dose that significantly reduced pulse rate by 27 +/- 2% had no effect on IHB or ISO2, suggesting that this dose of propranolol has no direct vasoactive effect on the gastric (splanchnic) circulation.

Animals↗
PubMedDate not supplied

Octreotide decreases canine gastric mucosal blood flow: a controlled assessment by endoscopic reflectance spectrophotometry.

The aim of this study was to evaluate the effects of octreotide, a long-acting somatostatin analogue, on canine gastric mucosal blood flow and hemodynamics. We hypothesized that octreotide might decrease gastric mucosal blood flow without causing adverse hemodynamic effects. Two groups of dogs were anesthetized (six normal dogs and six dogs with prehepatic portal hypertension), and each dog was administered intravenous octreotide, normal saline solution, and vasopressin for 30 minutes on separate days in a blinded, randomized fashion. Vasopressin was included as treatment for a positive control. Gastric mucosal blood flow was assessed at the fundus, corpus, and antrum by endoscopic reflectance spectrophotometry. A femoral arterial catheter monitored systemic blood pressure and heart rate. Treatment responses for all observations were calculated for each dog as a percentage of baseline values. For mucosal blood flow, treatment responses did not differ significantly over time or between animal group or gastric location. Octreotide significantly decreased indices of hemoglobin concentration (-19%, p = 0.01) and oxygen saturation (-17%, p = 0.0002) compared to saline (-9% and -7%, respectively). The mean arterial pressure was increased after octreotide compared to saline (+23% versus +7%, p = 0.01), but octrotide had no effect on heart rate (+2% versus +1%). Vasopressin also decreased the indices of hemoglobin concentration (-34%) and oxygen saturation (-82%) significantly more than saline (p = 0.001). Vasopressin increased mean arterial pressure (+55%), but also caused reflex bradycardia (-22%) significantly more than saline (p = 0.001). We conclude that octreotide decreases canine gastric mucosal blood flow and appears to cause minimal hemodynamic changes.

Animals↗
PubMedDate not supplied

Prospective randomized comparative study of bipolar versus direct current electrocoagulation for treatment of bleeding internal hemorrhoids.

Internal hemorrhoids are the most common cause of lower gastrointestinal bleeding. Although new anoscopic therapies are available, few comparative randomized studies have evaluated them in regard to long-term efficacy, recurrence rates, and safety. Our purpose was to compare the treatment of internal hemorrhoids with direct current (Ultroid, Cabot Medical, Langhorn, Pa.) and bipolar (BICAP, Circon ACMI, Stamford, Conn.) hemorrhoid probes. One hundred patients with symptomatic internal hemorrhoids were randomized: 50 to direct current electrocoagulation and 50 to bipolar electrocoagulation. Follow-up and treatment were at 3- to 4-weekly intervals; two to three hemorrhoid segments were treated at each session until relief of symptoms (bleeding, prolapse, and discharge) and a reduction in hemorrhoid size to grade 1 or 0 were noted. The hemorrhoids of 98% of all patients studied were grade 2 or 3; 2% of patients had grade 1 hemorrhoids and none had grade 4 hemorrhoids. At 1 year after treatment, most patients had no (69%) or only mild (23%) recurrence, and a few had severe, symptomatic (8%) hemorrhoid recurrence. A greater recurrence rate was noted after direct current treatment (34%) than bipolar treatment (29%). In contrast, rebleeding at 1 year occurred less frequently after direct current treatment (5%) than after bipolar treatment (20%). Our conclusions were as follows: (1) Both direct current and bipolar probes were effective for control of chronic bleeding from grade 1 to 3 internal hemorrhoids. (2) Bipolar probe was significantly faster than direct current probe. (3) Direct current treatment produced fewer complications than bipolar treatment (12% versus 14%). (4) Recurrence rates were low after 1 year with either device (8%).(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocoagulation↗