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Biomedical subjects

W F Bennett

Publications and source records attributed to W F Bennett.

At least 37 records · Page 2Linked to original sources
PubMed2000

Cable modem access to picture archiving and communication system images using a web browser over the Internet.

This presentation describes our experiences using a web-based viewing software and a browser to view our picture archiving and communication system (PACS) images at a remote site with cable modem-internet communications. Our testing shows that using a cable modem to access our radiology webserver produces acceptable transmission speeds to remote sites. The average time-to-display (TTD) for 16 computed tomography (CT) images on the web-based intranet system in our hospital was 7 to 8 seconds. Using a cable modem and comparable equipment at a remote site, the average TTD is 16 seconds over the internet. The TTD does not significantly change during various hours of the day. Security for our hospital-based PACS is provided by a firewall. Access through the firewall is accomplished using virtual private network (VPN) software, a secure ID, and encryption. We have found that this is a viable method for after-hours subspecialty radiology consultation.

Academic Medical Centers↗
PubMed2000

Addressing glenohumeral stiffness while treating the painful and stiff shoulder arthroscopically.

The shoulder can be primarily or secondarily stiff. Cadaveric cutting studies have shown increases in passive range of glenohumeral motion when certain portions of the capsule are released. This study has recorded the intraoperative gains made in passive range of motion for external rotation, flexion, abduction, and internal rotation with sequential release of the rotator interval, inferior capsule, and posterosuperior capsule, regardless of initial etiology, and followed-up over time. Thirty one of 60 shoulders, found clinically to have a loss of passive range of motion and having failed a nonoperative approach, underwent a capsular release. Eighteen patients underwent a partial capsular release (group 1) and 13 patients (group 2) underwent a complete capsular release. Thirty of 31 shoulders had statistically significant gains in passive range of motion with sequential release. In general, resection of the rotator interval contributed to gains in external rotation; resection of the inferior capsule (anteroinferior and posteroinferior) contributed gains to external rotation, forward flexion, and internal rotation; and resection of the posterosuperior capsule contributed to gains only in internal rotation. At a minimum of 18 months follow-up, 30 of 31 shoulders retained their intraoperative gains. There was no difference in the results between primarily and secondarily stiff shoulders for motion gains (P >.05). Arthroscopically addressing capsular tightness is beneficial in returning shoulders with a loss of passive glenohumeral motion to normal regardless of the etiology.

Adult↗
PubMed2000

Comparison of videothoracoscopy and axillary thoracotomy for the treatment of spontaneous pneumothorax.

Surgical treatment of spontaneous pneumothorax can be done through a thoracotomy or a video-thoracoscopic approach. Although the videothoracoscopic technique is currently popular it is not obviously superior to a more traditional axillary thoracotomy approach. We compared our recent experience with both techniques to determine the optimal surgical treatment for spontaneous pneumothoraces. A retrospective review of 79 patients treated surgically (34 thoracotomy and 45 thoracoscopy) for spontaneous pneumothoraces was done. Patients were treated between 1991 and 1997. Patients older than 60 years of age and those with spontaneous pneumothoraces secondary to generalized pulmonary emphysema were excluded. There were no operative deaths. Recurrence rate [thoracotomy, two of 34; thoracoscopy, three of 45 (P < 0.89)], air leak exceeding 7 days [thoracotomy, three of 34; thoracoscopy, three of 45 (P < 0.73)], operating room times [thoracotomy, 54 +/- 26 minutes; thoracoscopy, 53 +/- 16 minutes (P < 0.59)], and postoperative length of stay [thoracotomy, 5.7 +/- 4.3 days; thoracoscopy, 4.7 +/- 4.4 days (P < 0.26)] were not significantly different for the two techniques. We conclude that axillary thoracotomy and videothoracoscopy are equally effective surgical treatments for spontaneous pneumothoraces. A large randomized trial would be needed to determine whether one approach is truly superior to the other.

Adult↗
PubMed1999

Web-based viewing of picture archiving and communications systems images--Part I: Optimal personal computer configuration.

Now that picture archiving and communications systems (PACS) has matured, our challenge is to make the images available to the referring physician and, in a teaching institution, to make these images available for conferences and rounding. One solution is the distribution of the images using web-based technology. We investigated a web-based add-on to our PACS to determine the characteristics of the personal computer that will make this technology useful and affordable. We found that images can be viewed easily through a web-based system. We found that the optimal system to view these images at a reasonable speed and a reasonable cost is on with a medium-range processor (200 to 300 MHz) and a large amount of inexpensive RAM, at least 64 Mb.

Costs and Cost Analysis↗
PubMed1999

Web-based viewing of picture archiving and communications systems images--Part II: The effect of compression on speed of transmission.

Now that picture archiving and communications systems (PACS) has matured, our challenge is to make the images available to the referring physician and, in a teaching institution, to make these images available for conferences and rounding. One solution is the distribution of the images using web-based technology. We investigated a web-based add-on to our PACS to determine the characteristics of the personal computer that will make this technology useful and affordable. We found that images can be viewed easily through a web-based system. We found that the optimal system to view these images at a reasonable speed and a reasonable cost is on with a medium-range processor (200 to 300 MHz) and a large amount of inexpensive RAM, at least 64 Mb.

Data Display↗
PubMed1999

Compensatory renal growth in uninephrectomized adult mice is growth hormone dependent.

UNLABELLED: Compensatory renal growth in uninephrectomized adult mice is growth hormone dependent. BACKGROUND: Growth hormone (GH) and insulin-like growth factors (IGFs) have been implicated as pathogenic factors in compensatory renal growth (CRG) following unilateral nephrectomy in rodents. CRG in adult rats has been suggested to be GH dependent and GH independent in immature rats. However, the exact role of GH as a regulating or permissive factor in CRG in adult rodents has not been fully resolved to date. METHODS: To elucidate a possible direct, permissive role of GH in CRG, we examined the effect of a newly developed specific GH receptor (GHR) antagonist (G120K-PEG) on kidney IGF-I accumulation and renal/glomerular hypertrophy over seven days after uninephrectomy in adult mice. RESULTS: Placebo-treated uninephrectomized mice were characterized by a transient increase in kidney IGF-I concentration preceding CRG and an increase in glomerular volume. In G120K-PEG-treated uninephrectomized animals, increased kidney IGF-I levels, kidney weight, and glomerular volume were fully abolished. No differences were seen between the two uninephrectomized groups with respect to body weight, food intake, blood glucose, serum GH, IGF-I, or IGFBP-3 levels. CONCLUSIONS: The administration of a GHR antagonist in uninephrectomized adult mice has renal effects without affecting circulating levels of GH/IGFs, indicating that the effect of G120K-PEG may be mediated through a direct inhibitory effect on renal IGF-I accumulation through the renal GHR. This study shows, to our knowledge for the first time, that CRG in adult mice is strictly GH dependent.

Age Factors↗
PubMed1999

The human growth hormone antagonist B2036 does not interact with the prolactin receptor.

The human growth hormone (hGH) antagonist B2036 combines a single amino acid substitution impairing receptor binding site 2 (G120K) with eight additional amino acid substitutions that improve binding site 1 affinity. This hGH antagonist is being tested for treating pathologies linked to excess hGH levels. B2036-PEG is a polyethylene glycol (PEG) conjugated form of B2036 that has an increased half-life due to reduced renal clearance. It is currently in phase III trials for acromegaly. Human GH is also able to bind to the receptor of prolactin (PRLR). Since activation of PRLR can promote an array of pathological states (reproduction disorders, breast cancer), the ability of B2036-PEG to interact with the PRLR had to be determined. In this study, we compared four hGH antagonists (G120K, G120K-PEG, B2036 and B2036-PEG) in three bioassays: proliferation of rat Nb2 cells, binding to the human PRLR and activation of human PRLR-mediated signaling in a cell line stably expressing this receptor and a luciferase reporter gene. Agonistic and antagonistic properties were characterized. Our data show that B2036-PEG does not bind, activate or antagonize PRLRs, either from rat or human origin. These observations further demonstrate that the eight amino acid substitutions within binding site 1 provide binding specificity directed towards the human GH receptor.

Animals↗
PubMed1999

Growth hormone (GH) receptor blockade with a PEG-modified GH (B2036-PEG) lowers serum insulin-like growth factor-I but does not acutely stimulate serum GH.

B2036-PEG, a GH receptor (GH-R) antagonist, is an analog of GH that is PEG-modified to prolong its action. Nine mutations alter the binding properties of this molecule, preventing GH-R dimerization and GH action. A potential therapeutic role of B2036-PEG is to block GH action, e.g. in refractory acromegaly. A phase I, placebo-controlled, single rising-dose study was performed in 36 normal young men (ages, 18-37 yr; within 15% ideal body weight). Four groups received a single s.c. injection of either placebo (n = 3 in each group, total n = 12) or B2036-PEG (0.03, 0.1, 0.3, or 1.0 mg/kg; n = 6 each dose). B2036-PEG and GH concentrations were measured 0, 0.25, 0.5, 1, 3, 6, 9, 12, 24, 36, 48, 72, 96, 120, and 144 h after dosing. Serum insulin-like growth factor-I was measured before and 1-7 days after dosing. All doses were well tolerated, with no serious or severe adverse reactions. B2036-PEG, at 1.0 mg/kg, reduced insulin-like growth factor-I by 49 +/- 6% on day 5 (P < 0.001 vs. placebo). GH was measured by two independent methods: 1) modified Nichols chemiluminescence assay (empirically corrected for B2036-PEG cross-reactivity); and 2) direct GH two-site immunoassay, using monoclonal antibodies that did not react with B2036-PEG. There was good agreement between the two methods. GH did not change substantially at any B2036-PEG dose, suggesting that B2036-PEG does not interact with hypothalamic GH-Rs to block short-loop feedback. B2036-PEG may thus block peripheral GH action without enhancing its secretion.

Adolescent↗
PubMed1999

Comparison of no medication, placebo, and hyoscyamine for reducing pain during a barium enema.

OBJECTIVE: We carried out a prospective, randomized study to evaluate the usefulness of premedication with an oral anticholinergic for relief of pain during and after a barium enema of the colon. SUBJECTS AND METHODS: Patients were randomized into three groups: no medication, placebo, and sublingual 1-hyoscyamine sulfate. The placebo or hyoscyamine tablet was placed under the tongue 15-30 min before the examination. After the procedure the patients were interviewed. An analog scale (0-10) was used to score the level of pain that the patients experienced during the examination. Forty-eight hours after the examination, the patients returned by mail a survey that used the same scale and asked about delayed pain. RESULTS: Data from 110 patients were studied. Sixty-nine patients were women, and 41 were men. They ranged from 24 to 82 years old (mean, 55 years). For the no-medication group (n = 36), the mean pain score was 4.1; for the placebo group (n = 34), 3.8; and for the hyoscyamine group (n = 40), 4.2. No statistically significant difference in pain scores was found between any groups (p = .72). Six patients from each group reported minor side effects. The mean scores from the returned surveys (n = 79) were 3.8 for the no-medication group (n = 26) and placebo group (n = 22) and 3.1 for the hyoscyamine group (n = 31). No statistically significant difference was found between any of these groups (p = .48) or between delayed pain responses and initial pain responses (p = .27). CONCLUSION: Although safe, hyoscyamine seems to provide no benefit over no drug or a placebo when used as a pain premedication for patients undergoing a barium enema.

Atropine↗
PubMed1999

Inhibitory effect of a growth hormone receptor antagonist (G120K-PEG) on renal enlargement, glomerular hypertrophy, and urinary albumin excretion in experimental diabetes in mice.

Growth hormone (GH) and IGFs have a long and distinguished history in diabetes, with possible participation in the development of renal complications. To investigate the effect of a newly developed GH receptor (GHR) antagonist (G120K-PEG) on renal/glomerular hypertrophy and urinary albumin excretion (UAE), streptozotocin-induced diabetic and nondiabetic mice were injected with G120K-PEG every 2nd day for 28 days. Placebo-treated diabetic and nondiabetic animals were used as reference groups. Placebo-treated diabetic animals were characterized by growth retardation, hyperphagia, hyperglycemia, increased serum GH levels, reduced serum IGF-I, IGF-binding protein (IGFBP)-3, and liver IGF-I levels, increased kidney IGF-I, renal/glomerular hypertrophy, and increased UAE when compared with nondiabetic animals. No differences were seen between the two diabetic groups with respect to body weight, food intake, blood glucose, serum GH, IGF-I, and IGFBP-3 levels or hepatic IGF-I levels. Kidney IGF-I, kidney weight, and glomerular volume were normalized, while the rise in UAE was partially attenuated in the G120K-PEG-treated diabetic animals. No effect of G120K-PEG treatment on any of the parameters mentioned above was seen in nondiabetic animals. In conclusion, administration of a GHR antagonist in diabetic mice has renal effects without affecting metabolic control and circulating levels of GH, IGF-I, or IGFBP-3, thus indicating that the effect of G120K-PEG may be mediated through a direct inhibitory effect on renal IGF-I through the renal GHR. The present study suggests that specific GHR blockade may present a new concept in the treatment of diabetic kidney disease.

Albuminuria↗