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Y Chang

Publications and source records attributed to Y Chang.

At least 19 recordsLinked to original sources
PubMed2003

MSTAR: a submicrometer absolute metrology system.

The Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor permits absolute distance measurement with subnanometer accuracy, an improvement of 4 orders of magnitude over current techniques. The system uses fast phase modulators to resolve the integer cycle ambiguity of standard interferometers. The concept is described and demonstrated over target distances up to 1 m. The design can be extended to kilometer-scale separations.

Journal Article↗
PubMed2003

High frequency plant regeneration from immature embryos of an elite barley cultivar (Hordeum vulgare L. cv. Morex).

An efficient plant regeneration system was developed for Hordeum vulgare L. 'Morex' barley, an important United States malting cultivar. The protocol was based on a series of experiments involving the sizes of immature embryos and the culture media. We found that the embryo size is critical for the establishment of embryogenic callus. Smaller embryos (0.5-1.5 mm) showed a much higher ability to produce embryogenic callus capable of regenerating green plants with fewer albinos than did the larger embryos (1.6-3.0 mm). Either 3 mg/l 2,4-dichlorophenoxyacetic acid or dicamba in modified Murashige and Skoog's (MS) medium was optimum for the induction of embryogenic callus. The embryogenic callus maintained high regeneration during six subcultures in the callus induction medium. Efficient shoot regeneration was obtained on modified MS medium containing 0.5-1.0 mg/l 6-benzylaminopurine (BA). Regenerated shoots were rooted on half-strength MS medium containing 0.2 mg/l IBA. Plants were successfully transferred to soil and grown to maturity in the greenhouse. This efficient plant regeneration system provides a foundation for generating transgenic plants of this important barley cultivar.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2002

Pharmacodynamics of mivacurium chloride in 13- to 18-yr-old adolescents with thermal injury.

BACKGROUND: Burned patients demonstrate resistance to the effects of non-depolarizing blocking drugs as a result of acetylcholine receptor changes. They also have decreased activity of plasma cholinesterase (PCHE), which metabolizes mivacurium. We hypothesized that decreased PCHE activity would decrease metabolism of mivacurium, and counteract the receptor-related resistance following burns. METHODS: Thirteen burned patients and six controls, aged 13-18 yr were followed in 27 studies. The burned patients were sub-classified as having 10-30% or >30% body surface area burn and were studied whenever possible at < or =6 days, and at 1-12 weeks after the burn. Mivacurium pharmacodynamics were examined following a bolus (0.15 mg kg(-1)) dose, and during and after a continuous infusion. RESULTS: Following a bolus, the onset time and the maximal effect were similar to controls. Recovery was prolonged in the 10-30% burn group at 1-12 weeks (P<0.008), with a similar trend in the >30% burn group at < or =6 days (P<0.082) compared with controls. The infusion requirements for mivacurium were not increased in the burned groups. The PCHE activity was decreased in all burn groups and was inversely related to recovery following the bolus (r=0.73, P<0.001) and the infusion (r=0.69, P<0.001). CONCLUSION: In contrast to previous studies with non-depolarizers in burned patients, normal mivacurium doses can produce paralysis, at least as rapidly as in controls, but with a possibility of a prolonged recovery from block. The standard dose of mivacurium in the presence of decreased PCHE activity is in effect, a relative overdose that explains the above findings. Mivacurium is an effective drug for use in burns, irrespective of time after, or magnitude of burn injury.

Adolescent↗
PubMed2001

Molecular anatomy of CCR5 engagement by physiologic and viral chemokines and HIV-1 envelope glycoproteins: differences in primary structural requirements for RANTES, MIP-1 alpha, and vMIP-II Binding.

Molecular analysis of CCR5, the cardinal coreceptor for HIV-1 infection, has implicated the N-terminal extracellular domain (N-ter) and regions vicinal to the second extracellular loop (ECL2) in this activity. It was shown that residues in the N-ter are necessary for binding of the physiologic ligands, RANTES (CCL5) and MIP-1 alpha (CCL3). vMIP-II, encoded by the Kaposi's sarcoma-associated herpesvirus, is a high affinity CCR5 antagonist, but lacks efficacy as a coreceptor inhibitor. Therefore, we compared the mechanism for engagement by vMIP-II of CCR5 to its interaction with physiologic ligands. RANTES, MIP-1 alpha, and vMIP-II bound CCR5 at high affinity, but demonstrated partial cross-competition. Characterization of 15 CCR5 alanine scanning mutants of charged extracellular amino acids revealed that alteration of acidic residues in the distal N-ter abrogated binding of RANTES, MIP-1 alpha, and vMIP-II. Whereas mutation of residues in ECL2 of CCR5 dramatically reduced the binding of RANTES and MIP-1 alpha and their ability to induce signaling, interaction with vMIP-II was not altered by any mutation in the exoloops of the receptor. Paradoxically, monoclonal antibodies to N-ter epitopes did not block chemokine binding, but those mapped to ECL2 were effective inhibitors. A CCR5 chimera with the distal N-ter residues of CXCR2 bound MIP-1 alpha and vMIP-II with an affinity similar to that of the wild-type receptor. Engagement of CCR5 by vMIP-II, but not RANTES or MIP-1 alpha blocked the binding of monoclonal antibodies to the receptor, providing additional evidence for a distinct mechanism for viral chemokine binding. Analysis of the coreceptor activity of randomly generated mouse-human CCR5 chimeras implicated residues in ECL2 between H173 and V197 in this function. RANTES, but not vMIP-II blocked CCR5 M-tropic coreceptor activity in the fusion assay. The insensitivity of vMIP-II binding to mutations in ECL2 provides a potential rationale to its inefficiency as an antagonist of CCR5 coreceptor activity. These findings suggest that the molecular anatomy of CCR5 binding plays a critical role in antagonism of coreceptor activity.

Alanine↗
PubMed2001

Leaving gatekeeping behind--effects of opening access to specialists for adults in a health maintenance organization.

BACKGROUND: Gatekeeping refers to the prior approval of referrals to specialists by a primary care physician. Although many health plans view gatekeeping as an essential tool for controlling costs and coordinating care, many patients and physicians object to it. METHODS: On April 1, 1998, Harvard Vanguard Medical Associates, a large, multispecialty, capitated group practice previously known as Harvard Community Health Plan, eliminated a gatekeeping system that had been in place for over 25 years. We determined the effects of opening access to specialists on visits to primary care physicians and specialists by adults. In randomly selected cohorts of 10,000 members each, we analyzed visits during 6-month periods for the 3 years before and 18 months after gatekeeping was eliminated. RESULTS: Adults visited a primary care physician an average of 1.21 times and 1.19 times per six-month period before and after the elimination of gatekeeping, respectively (P=0.05); the average number of visits to a specialist was 0.78 per six-month period both before and after its elimination (P=0.35). There was little change in the percentage of visits to specialists included in the analysis as a proportion of all visits (39.1 percent before the elimination of gatekeeping and 39.5 percent afterward). The percentage of first visits to specialists as a proportion of all visits to specialists included in the analysis increased from 24.7 to 28.2 percent (P<0.001). There were small increases in the numbers of visits to orthopedists and physical or occupational therapists. The proportion of visits to specialists for low back pain that were new consultations increased from 26.6 to 32.9 percent (P=0.01). CONCLUSIONS: In a capitated, multispecialty group practice, we found little evidence of substantial changes in the use of specialty services by adults in the first 18 months after the elimination of gatekeeping.

Adult↗
PubMed2001

Alpha-lipoic acid protects rat cortical neurons against cell death induced by amyloid and hydrogen peroxide through the Akt signalling pathway.

Substantial evidence suggests that the accumulation of beta-amyloid (Abeta)-derived peptides contributes to the aetiology of Alzheimer's disease (AD) by stimulating formation of free radicals. Thus, the antioxidant alpha-lipoate, which is able to cross the blood-brain barrier, would seem an ideal substance in the treatment of AD. We have investigated the potential effectiveness of alpha-lipoic acid (LA) against cytotoxicity induced by Abeta peptide (31-35) (30 microM) and hydrogen peroxide (H(2)O(2)) (100 microM) with the cellular 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) reduction and fluorescence dye propidium iodide assays in primary neurons of rat cerebral cortex. We found that treatment with LA protected cortical neurons against cytotoxicity induced by Abeta or H(2)O(2). In addition, LA-induced increase in the level of Akt in the neurons was observed by Western blot. The LA-induced neuroprotection and Akt increase were attenuated by pre-treatment with the phosphatidylinositol 3-kinase inhibitor, LY294002 (50 microM). Our data suggest that the neuroprotective effects of the antioxidant LA are partly mediated through activation of the PKB/Akt signaling pathway.

Alzheimer Disease↗
PubMed2001

Positive allosteric modulation by ultraviolet irradiation on GABA(A), but not GABA(C), receptors expressed in Xenopus oocytes.

1. Recombinant rat GABA(A) (alpha1beta2, alpha1beta2gamma2, beta2gamma2) and human GABA(C) (rho1) receptors were expressed in Xenopus oocytes to examine the effect of ultraviolet (UV) light on receptor function. 2. GABA-induced currents in individual oocytes expressing GABA receptors were tested by two-electrode voltage clamp before, and immediately after, 312 nm UV irradiation. 3. UV irradiation significantly potentiated 10 microM GABA-induced currents in alpha1beta2gamma2 GABA receptors. The modulation was irradiation dose dependent, with a maximum potentiation of more than 3-fold. 4. The potentiation was partially reversible and decayed exponentially with a time constant of 8.2 +/- 1.2 min toward a steady-state level which was still significantly elevated (2.7 +/- 0.3-fold) compared to the control level. 5. The effect of UV irradiation on GABA(A) receptors varied with receptor subunit composition. UV irradiation decreased the EC50 of the alpha1beta2, alpha1beta2gamma2 and beta2gamma2 GABA(A) receptors, but exhibited no significant effect on the rho1 GABA(C) receptor. 6. UV irradiation also significantly increased the maximum current 2-fold in alpha1beta2 GABA(A) receptors with little effect on the maximum of alpha1beta2gamma2 (1.1-fold) or beta2gamma2 (1.1-fold) GABA(A) receptors. 7. The effect of UV irradiation on GABA(A) receptors did not overlap the effect of the GABA receptor- allosteric modulator, diazepam. 8. The UV effect on GABA(A) receptors was not prevented by the treatment of the oocytes before and during UV irradiation with one of the following free-radical scavengers: 40 mM D-mannitol, 40 mM imidazole or 40 mM sodium azide. In addition, the effect was not mimicked by the free-radical generator, H2O2. 9. Potential significance and mechanism(s) of the UV effect on GABA receptors are discussed.

Allosteric Regulation↗
PubMed2001

Retraction.

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Retraction Notice↗
PubMed2001

Processes of care, illness severity, and outcomes in the management of community-acquired pneumonia at academic hospitals.

BACKGROUND: Prompt antibiotic administration, oxygenation measurement, and blood cultures are generally considered markers of high-quality care in the inpatient management of community-acquired pneumonia (CAP). However, few studies have examined the relationship between prompt achievement of process-of-care markers and outcomes for patients with CAP. We examined whether antibiotic administration within 8 hours of hospital arrival, a blood culture within 24 hours, an oxygenation measurement within 24 hours, or performing blood cultures before giving antibiotics was associated with the following: (1) reaching clinical stability within 48 hours of hospital admission, (2) a decreased length of hospital stay, or (3) fewer inpatient deaths. METHODS: A retrospective medical record review identified 1062 eligible patients discharged from the hospital with a diagnosis of CAP between December 1, 1997, and February 28, 1998, among 38 US academic hospitals. We assessed the independent relationship between each process marker and the 3 clinical outcomes, controlling for the Pneumonia Severity Index on admission. We also examined the relationship of pneumonia severity on admission to process marker achievement and clinical outcomes. RESULTS: Overall, there was no consistent or statistically significant relationship between achieving process markers and better clinical outcomes (P>.40 for all). We did observe that performing blood cultures within 24 hours was related to not achieving clinical stability within 48 hours (odds ratio, 1.62; 95% confidence interval, 1.13-2.33). However, this finding likely reflects residual confounding by severity of illness, since increasing pneumonia severity on admission was associated with blood culture performance (P =.009) and with shorter times to antibiotic administration (P =.04). CONCLUSIONS: Achieving process-of-care markers was not associated with improved outcomes, but was related to the severity of pneumonia as assessed on admission. Our results highlight the difficulty in demonstrating a link between process-of-care markers and outcomes in observational studies of CAP. Randomized studies are needed to objectively evaluate the impact of process-of-care markers on CAP outcomes.

Aged↗
PubMed2001

Fever in subarachnoid hemorrhage: relationship to vasospasm and outcome.

OBJECTIVE: To investigate the causes of fever in subarachnoid hemorrhage (SAH) and examine its relationship to outcome. BACKGROUND: Fever adversely affects outcome in stroke. Patients with SAH are at risk for cerebral ischemia due to vasospasm (VSP). In these patients, fever may be both caused by, and potentiate, VSP-mediated brain injury. METHODS: The authors prospectively studied patients admitted to a neurologic intensive care unit with nontraumatic SAH, documenting Hunt-Hess grade, Fisher group, Glasgow Coma Score, bacterial culture data, daily transcranial Doppler mean velocities, and maximum daily temperatures. Patients were classified as febrile (temperature above 38.3 degrees C for at least 2 consecutive days) or afebrile (no fever or isolated episodes of temperature above 38.3 degrees C). VSP was verified by either transcranial Doppler or angiographic criteria. Rankin scale scores on discharge were dichotomized into good (0 to 2) or poor (3 to 6) outcomes. RESULTS: Ninety-two consecutive patients were studied. Thirty-eight patients were classified as febrile. No source for infection was found in 10 of 38 (26%) patients. In a multivariate analysis, three variables independently predicted fever occurrence: ventriculostomy (OR, 8.5 [CI, 2.4 to 29.7]), symptomatic VSP (OR, 5.0 [CI, 1.03 to 24.5]), and older age (OR, 1.75 per 10 years [CI, 1.02 to 3.0]). Poor outcome was related to fever (OR, 1.4 per each day febrile [CI, 1.1 to 1.88]), older age (OR, 1.64 per 10 years [CI, 1.04 to 2.58]), and intubation (OR, 21.8 [CI, 5.6 to 84.5]). CONCLUSION: Fever in SAH is associated with vasospasm and poor outcome independently of hemorrhage severity or presence of infection.

Adult↗
PubMed2001

Surgical and nonsurgical management of sciatica secondary to a lumbar disc herniation: five-year outcomes from the Maine Lumbar Spine Study.

STUDY DESIGN: A prospective cohort study. OBJECTIVE: To assess 5-year outcomes for patients with sciatica caused by a lumbar disc herniation treated surgically or nonsurgically. SUMMARY OF BACKGROUND DATA: There is limited knowledge about long-term treatment outcomes of sciatica caused by a lumbar disc herniation, particularly the relative benefits of surgical and conservative therapy in contemporary clinical practice. METHODS: Eligible, consenting patients recruited from the practices of orthopedic surgeons, neurosurgeons, and occupational medicine physicians throughout Maine had baseline interviews with mailed follow-up questionnaires at 3, 6, and 12 months and annually thereafter. Clinical data were obtained at baseline from a physician questionnaire. Outcomes included patient-reported symptoms of leg and back pain, functional status, satisfaction, and employment and compensation status. RESULTS: Of 507 patients initially enrolled, 5-year outcomes were available for 402 (79.3%) patients: 220 (80%) treated surgically and 182 (78.4%) treated nonsurgically. Surgically treated patients had worse baseline symptoms and functional status than those initially treated nonsurgically. By 5 years 19% of surgical patients had undergone at least one additional lumbar spine operation, and 16% of nonsurgical patients had opted for at least one lumbar spine operation. Overall, patients treated initially with surgery reported better outcomes. At the 5-year follow-up, 70% of patients initially treated surgically reported improvement in their predominant symptom (back or leg pain) versus 56% of those initially treated nonsurgically (P < 0.001). Similarly, a larger proportion of surgical patients reported satisfaction with their current status (63% vs. 46%, P < 0.001). These differences persisted after adjustment for other determinants of outcome. The relative advantage of surgery was greatest early in follow-up and narrowed over 5 years. There was no difference in the proportion of patients receiving disability compensation at the 5-year follow-up. The least symptomatic patients at baseline did well regardless of initial treatment, although function improved more in the surgical group. CONCLUSIONS: For patients with moderate or severe sciatica, surgical treatment was associated with greater improvement than nonsurgical treatment at 5 years. However, patients treated surgically were as likely to be receiving disability compensation, and the relative benefit of surgery decreased over time.

Adult↗
PubMed2001

Prevalence of diagnosed atrial fibrillation in adults: national implications for rhythm management and stroke prevention: the AnTicoagulation and Risk Factors in Atrial Fibrillation (ATRIA) Study.

CONTEXT: Atrial fibrillation is the most common arrhythmia in elderly persons and a potent risk factor for stroke. However, recent prevalence and projected future numbers of persons with atrial fibrillation are not well described. OBJECTIVE: To estimate prevalence of atrial fibrillation and US national projections of the numbers of persons with atrial fibrillation through the year 2050. DESIGN, SETTING, AND PATIENTS: Cross-sectional study of adults aged 20 years or older who were enrolled in a large health maintenance organization in California and who had atrial fibrillation diagnosed between July 1, 1996, and December 31, 1997. MAIN OUTCOME MEASURES: Prevalence of atrial fibrillation in the study population of 1.89 million; projected number of persons in the United States with atrial fibrillation between 1995-2050. RESULTS: A total of 17 974 adults with diagnosed atrial fibrillation were identified during the study period; 45% were aged 75 years or older. The prevalence of atrial fibrillation was 0.95% (95% confidence interval, 0.94%-0.96%). Atrial fibrillation was more common in men than in women (1.1% vs 0.8%; P<.001). Prevalence increased from 0.1% among adults younger than 55 years to 9.0% in persons aged 80 years or older. Among persons aged 50 years or older, prevalence of atrial fibrillation was higher in whites than in blacks (2.2% vs 1.5%; P<.001). We estimate approximately 2.3 million US adults currently have atrial fibrillation. We project that this will increase to more than 5.6 million (lower bound, 5.0; upper bound, 6.3) by the year 2050, with more than 50% of affected individuals aged 80 years or older. CONCLUSIONS: Our study confirms that atrial fibrillation is common among older adults and provides a contemporary basis for estimates of prevalence in the United States. The number of patients with atrial fibrillation is likely to increase 2.5-fold during the next 50 years, reflecting the growing proportion of elderly individuals. Coordinated efforts are needed to face the increasing challenge of optimal stroke prevention and rhythm management in patients with atrial fibrillation.

Adult↗
PubMed2001

Molecular virology of Kaposi's sarcoma-associated herpesvirus.

Kaposi's sarcoma-associated herpesvirus (KSHV), the most recently discovered human tumour virus, is the causative agent of Kaposi's sarcoma, primary effusion lymphoma and some forms of Castleman's disease. KSHV is a rhadinovirus, and like other rhadinoviruses, it has an extensive array of regulatory genes obtained from the host cell genome. These pirated KSHV proteins include homologues to cellular CD21, three different beta-chemokines, IL-6, BCL-2, several different interferon regulatory factor homologues, Fas-ligand ICE inhibitory protein (FLIP), cyclin D and a G-protein-coupled receptor, as well as DNA synthetic enzymes including thymidylate synthase, dihydrofolate reductase, DNA polymerase, thymidine kinase and ribonucleotide reductases. Despite marked differences between KSHV and Epstein-Barr virus, both viruses target many of the same cellular pathways, but use different strategies to achieve the same effects. KSHV proteins have been identified which inhibit cell-cycle regulation checkpoints, apoptosis control mechanisms and the immune response regulatory machinery. Inhibition of these cellular regulatory networks app ears to be a defensive means of allowing the virus to escape from innate antiviral immune responses. However, due to the overlapping nature of innate immune and tumour-suppressor pathways, inhibition of these regulatory networks can lead to unregulated cell proliferation and may contribute to virus-induced tumorigenesis.

Animals↗
PubMed2001

Down-regulation of vascular endothelial growth factor by tissue inhibitor of metalloproteinase-2: effect on in vivo mammary tumor growth and angiogenesis.

The tissue inhibitor of metalloproteinases-2 (TIMP-2) has at least two independent functions, i.e., regulation of matrix metalloproteinases and growth promoting activity. We investigated the effects of TIMP-2 overexpression, induced by retroviral mediated gene transfer, on the in vivo development of mammary tumors in syngeneic mice inoculated with EF43.fgf-4 cells. The EF43.fgf-4 cells established by stably infecting the normal mouse mammary EF43 cells with a retroviral expression vector for the fgf-4 oncogene, are highly tumorigenic and overproduce vascular endothelial growth factor (VEGF). Despite a promotion of the in vitro growth rate of EF43.fgf-4 cells overexpressing timp-2, the in vivo tumor growth was delayed. At day 17 post-cell injection, the volume of tumor derived from TIMP-2-overexpressing cells was reduced by 80% as compared with that obtained with control cells. Overexpression of TIMP-2 was associated with a down-regulation of VEGF expression in vitro and in vivo, a reduction of vessel size, density, and blood supply in the induced tumors. In addition, TIMP-2 completely inhibited the angiogenic activity of EF43.fgf-4 cell-conditioned medium in vitro using a rat aortic ring model. Our findings suggest that overexpression of TIMP-2 delays growth and angiogenesis of mammary carcinoma in vivo and that down-regulation of VEGF expression may play an important role in this TIMP-2-mediated antitumoral and antiangiogenic effects. Finally the in vivo delivery of TIMP-2, as assessed by i.v. injection of recombinant adenoviruses vectors, significantly reduced the growth of the EF43.fgf-4-induced tumors. This effect of TIMP-2 was shown to be equally comparable with that of angiostatin, a known potent inhibitor of angiogenesis.

Adenoviridae↗
PubMed2001

Fudenine, a C-terminal truncated rat homologue of mouse prominin, is blood glucose-regulated and can up-regulate the expression of GAPDH.

Messenger RNA differential display was applied to screen for the blood glucose-regulated genes in SD rat skeletal muscle. The rat homologue of the mouse prominin was thus identified. Comparing to its mouse and human homologues, fudenine was C-terminal truncated due to a single nucleotide deletion. However, its mitochondrial energy transfer signature peptide PQDLVKKLI remained intact. Fudenine, an 592-amino acid containing, 66-kDa glycoprotein, is a novel plasma membrane protein with four transmembrane segments flanking by two large glycosylated extracellular domains. Although it is devoid of the last transmembrane domain comparing to its homologues, fudenine also locates in cell membrane by transfection of fusion plasmid pFudenine-EGFP into CBRH7919 cell and L-6TG cell. Overexpression of fudenine in CBRH7919 cell line up-regulated the mRNA level of GAPDH (3-phosphate glyceraldehyde dehydrogenase), while long-term glucose exposure resulted to reduced GAPDH expression. Since high blood glucose level induced the expression of fudenine in skeletal muscle, which in turn up-regulated the expression of GAPDH, we propose that fudenine might be a candidate gene for diabetes mellitus.

AC133 Antigen↗
PubMed2001

Mutations in sialidosis impair sialidase binding to the lysosomal multienzyme complex.

Sialidosis is an autosomal recessive disease caused by the genetic deficiency of lysosomal sialidase, which catalyzes the catabolism of sialoglycoconjugates. The disease is associated with progressive impaired vision, macular cherry-red spots, and myoclonus (sialidosis type I) or with skeletal dysplasia, Hurler-like phenotype, dysostosis multiplex, mental retardation, and hepatosplenomegaly (sialidosis type II). We analyzed the effect of the missense mutations G68V, S182G, G227R, F260Y, L270F, A298V, G328S, and L363P, which are identified in the sialidosis type I and sialidosis type II patients, on the activity, stability, and intracellular distribution of sialidase. We found that three mutations, F260Y, L270F, and A298V, which are clustered in the same region on the surface of the sialidase molecule, dramatically reduced the enzyme activity and caused a rapid intralysosomal degradation of the expressed protein. We suggested that this region might be involved in sialidase binding with lysosomal cathepsin A and/or beta-galactosidase in the multienzyme lysosomal complex required for the expression of sialidase activity. Transgenic expression of mutants followed by density gradient centrifugation of cellular extracts confirmed this hypothesis and showed that sialidase deficiency in some sialidosis patients results from disruption of the lysosomal multienzyme complex.

Amino Acid Sequence↗
PubMed2001

Ten-year experience with 733 pancreatic resections: changing indications, older patients, and decreasing length of hospitalization.

HYPOTHESIS: Experience with pancreatic resection for the last 10 years has resulted in new trends in patient characteristics and, for pancreaticoduodenectomy (PD), a decrease in the length of stay (LOS). This decrease is due in part to the implementation of case management and clinical pathways. DESIGN: Retrospective case series of patients undergoing pancreatic resection. SETTING: A university-affiliated, tertiary care referral center. PATIENTS: The study comprised 733 consecutive patients undergoing pancreatic resection for benign or malignant disease at the Massachusetts General Hospital in Boston from April 1990 to March 2000. INTERVENTIONS: Of the 733 pancreatic resections, 489 were PD; 190, distal pancreatectomy; 40, total pancreatectomy; and 14, middle-segment pancreatectomy. MAIN OUTCOME MEASURES: Length of stay; occurrence of delayed gastric emptying, pancreatic fistula, reoperation, readmission, or other complications; mortality; and comparison of patients in 3 periods according to the implementation of case management (July 1995) and clinical pathways (September 1998). RESULTS: For PD, patients in group 1 (April 1990 to June 1995) were significantly younger (mean +/- SD, 57 +/- 15 years) than those in group 2 (July 1995 to August 1998; mean +/- SD, 62 +/- 13 years) and group 3 (September 1998 to October 2000; mean +/- SD, 65 +/- 13 years)(P <.01). Over time, the proportion of PD for cystic tumors increased from 9.9% to 20% (P =.01), and the proportion of PD for chronic pancreatitis decreased from 23% to 10% (P <.01). Use of pylorus-preserving PD decreased from 45% to 0% (P <.001). Delayed gastric emptying decreased from 17% to 6.1% (P <.01). Pancreatic fistula, reoperation, and mortality were unchanged. Length of stay for PD decreased from 16.1 +/- 0.6 to 9.5 +/- 0.4 days (mean +/- SE) (P <.001). Multivariate analysis showed that period, case volume, pylorus-preserving PD, and presence of complications are all independent predictors of LOS (P <.05 for all). For distal pancreatectomy, patients in groups 2 and 3 were older than those in group 1 (mean +/- SD, 57 +/-14 vs 52 +/- 17 years) (P <.05). Resections for cystic tumors increased from 26% to 52% (P <.05), and resections for chronic pancreatitis decreased from 32% to 14% (P =.06). Median LOS decreased from 9 days to 6. For total pancreatectomy, resections for cystic tumors increased from 18% to 43%. Median LOS decreased from 14.5 days to 11. For all resections, case volume increased from 4 resections per month in 1990 to 5.8 in 1995 and 12 in 2000 (r = 0.83; P <.001). CONCLUSIONS: Older patients are increasingly being selected for pancreatic resection. This reflects an increasing frequency of operations performed for cystic tumors and fewer for chronic pancreatitis. With the exception of delayed gastric emptying, complications and mortality have remained the same or decreased slightly during the past 10 years. However, there has been a significant decrease in LOS; this is the result of implementation of case management and clinical pathways, increasing case volume, decreasing incidence of delayed gastric emptying, and decreasing use of pylorus-preserving PD.

Adenocarcinoma↗