Sex and racial disparities in non-alcoholic fatty liver disease-related cardiovascular events: National inpatient sample analysis (2019)

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) increases cardiovascular disease (CVD) risk irrespective of other risk factors. However, large-scale cardiovascular sex and race differences are poorly understood.

AIM

To investigate the relationship between NAFLD and major cardiovascular and cerebrovascular events (MACCE) in subgroups using a nationally representative United States inpatient sample.

METHODS

We examined National Inpatient Sample (2019) to identify adult hospitalizations with NAFLD by age, sex, and race using ICD-10-CM codes. Clinical and demographic characteristics, comorbidities, and MACCE-related mortality, acute myocardial infarction (AMI), cardiac arrest, and stroke were compared in NAFLD cohorts by sex and race. Multivariable regression analyses were adjusted for sociodemographic characteristics, hospitalization features, and comorbidities.

RESULTS

We examined 409130 hospitalizations [median 55 (IQR 43-66) years] with NFALD. NAFLD was more common in females (1.2%), Hispanics (2%), and Native Americans (1.9%) than whites. Females often reported non-elective admissions, Medicare enrolment, the median age of 55 (IQR 42-67), and poor income. Females had higher obesity and uncomplicated diabetes but lower hypertension, hyperlipidemia, and complicated diabetes than males. Hispanics had a median age of 48 (IQR 37-60), were Medicaid enrollees, and had non-elective admissions. Hispanics had greater diabetes and obesity rates than whites but lower hypertension and hyperlipidemia. MACCE, all-cause mortality, AMI, cardiac arrest, and stroke were all greater in elderly individuals (P < 0.001). MACCE, AMI, and cardiac arrest were more common in men (P < 0.001). Native Americans (aOR 1.64) and Asian Pacific Islanders (aOR 1.18) had higher all-cause death risks than whites.

CONCLUSION

Increasing age and male sex link NAFLD with adverse MACCE outcomes; Native Americans and Asian Pacific Islanders face higher mortality, highlighting a need for tailored interventions and care.

Intersection of sepsis, atrial fibrillation, and severe obesity: a population-based analysis in the United States

BACKGROUND

Atrial fibrillation (AF) is an indicator of poor prognosis in patients with sepsis and can increase the risk of stroke and mortality. Data on the impact of severe obesity on the outcomes of sepsis complicated by AF remains poorly understood.

METHODS

National Inpatient Sample (2018) and ICD-10 CM codes were used to identify the principal sepsis admissions with AF. We assessed comorbidities and outcomes of sepsis in people without obesity (BMI < 30) vs. non-severe obesity (BMI 30-35) and severe obesity (BMI > 35) cohorts. We also did a subgroup analysis to further stratify obesity based on metabolic health and analyzed the findings. The primary outcomes were the prevalence and adjusted odds of AF, AF-associated stroke, and all-cause mortality in sepsis by obesity status. Multivariable regression analyses were adjusted for patient- and hospital-level characteristics and comorbidities.

RESULTS

Our main analysis showed that of the 1,345,595 sepsis admissions, the severe obesity cohort was the youngest (median age 59 vs. non-severe 64 and people without obesity 68 years). Patients with obesity, who were often female, were more likely to have hypertension, diabetes, congestive heart failure, chronic pulmonary disease, and chronic kidney disease. The crude prevalence of AF was highest in non-severe obesity (19.9%). The adjusted odds of AF in non-severe obesity (OR 1.21; 95% CI:1.16-1.27) and severe obesity patients with sepsis (OR 1.49; 95% CI:1.43-1.55) were significantly higher than in people without obesity (p < 0.001). Paradoxically, the rates of AF-associated stroke (1%, 1.5%, and 1.7%) and in-hospital mortality (3.3%, 4.9%, and 7.1%) were lowest in the severe obesity cohort vs. the non-severe and people without obesity cohorts, respectively. On multivariable regression analyses, the all-cause mortality revealed lower odds in sepsis-AF patients with severe obesity (OR 0.78; 95% CI:0.67-0.91) or non-severe obesity (OR 0.63; 95% CI:0.54-0.74) vs. people without obesity. There was no significant difference in stroke risk.

CONCLUSIONS

A higher prevalence of cardiovascular comorbidities can be linked to a higher risk of AF in people with obesity and sepsis. Paradoxically, lower rates of stroke and all-cause mortality secondary to AF in people with obesity and sepsis warrant further investigation.

Association of Prediabetes and Recurrent Stroke in Atrial Fibrillation Patients: A Population-Based Analysis of Hospitalizations and Outcomes

Prediabetes is a risk factor for ischemic stroke in atrial fibrillation (AF) patients, yet, its impact on recurrent stroke in AF patients remains understudied. Using the 2018 National Inpatient Sample, we investigated the link between Prediabetes and recurrent stroke in AF patients with prior stroke or transient ischemic attack (TIA). Among 18,905 non-diabetic AF patients, 480 (2.5%) had prediabetes. The prediabetic group, with a median age of 78, exhibited a two-fold higher risk of recurrent stroke compared to the non-prediabetic cohort (median age 82), as evidenced by both unadjusted (OR 2.14, 95% CI 1.72-2.66) and adjusted (adjusted for socio-demographics/comorbidities, OR 2.09, 95% CI 1.65-2.64, p < 0.001). The prediabetes cohort, comprising more male and Black patients, demonstrated associations with higher Medicaid enrollment, admissions from certain regions, and higher rates of hyperlipidemia, smoking, peripheral vascular disease, obesity, and chronic obstructive pulmonary disease (all p < 0.05). Despite higher rates of home health care and increased hospital costs in the prediabetes group, the adjusted odds of all-cause mortality were not statistically significant (OR 0.55, 95% CI 0.19-1.56, p = 0.260). The findings of this study suggest that clinicians should be vigilant in managing prediabetes in AF patients, and strategies to prevent recurrent stroke in this high-risk population should be considered.

Rasburicase in treating tumor lysis syndrome: An umbrella review

Tumor lysis syndrome (TLS) remains a debilitating cause of hospitalization and death in patients with cancer and is a significant challenge for healthcare providers despite advancements in its management. This umbrella review analyzed the results of meta-analyses on the use of rasburicase in the treatment of patients with cancer. A literature search was performed of five databases (PubMed, Google Scholar, Cochrane Library, Scopus, Global Index Medicus, and ScienceDirect) for articles with full texts available online. A measurement tool to assess systematic reviews 2 (AMSTAR 2) was used to assess the quality of the included studies, and Review Manager software was used to conduct all statistical analyses. The systematic search identified eight relevant meta-analyses, with primary analyses including outcome data that analyzed mortality, renal failure, and comparisons with allopurinol. The pooled data showed that rasburicase effectively reduced TLS development and serum uric acid levels in children and adults with malignancies. Most outcomes did not differ significantly compared with those of allopurinol. Future trials should focus on the cost-effectiveness of rasburicase compared to that of allopurinol while including high-, intermediate-, and low-risk patients. Rasburicase is safe and effective for managing patients with TLS. However, recent large-scale meta-analyses have reported conflicting results. Most meta-analyses were graded as low to critically low as per AMSTAR 2. The analysis revealed that the benefit of rasburicase did not differ significantly from that of allopurinol, which has higher cost-effectiveness and fewer side effects.

Acute Myocardial Infarction-Related Hospitalizations in Non-elderly Patients with Pneumonia: a Population-Based Study

The objective is to study factors that increase the likelihood of acute myocardial infarction (AMI) in hospitalized adult non-elderly patients with pneumonia compared to other medical inpatients and to understand the utilization rate of percutaneous coronary intervention (PCI) for AMI in inpatients with pneumonia and its related impact on hospitalization stay and cost. A population-based study was conducted using the Nationwide Inpatient Sample (NIS, 2019) with adult non-elderly inpatients (age 18-65 years) with a medical condition as their primary diagnosis and a co-diagnosis of pneumonia during hospitalization stay. This study sample was divided by the primary diagnosis of AMI versus other medical conditions (non-AMI). A logistic regression model was used to evaluate the odds ratio (OR) of predictors associated with AMI in patients with pneumonia. The results showed a direct relationship between increasing age and the likelihood of AMI in pneumonia inpatients with three times higher odds seen in 51-65 years of age (OR 2.95, 95% CI 2.82-3.09). The comorbidities included complicated hypertension (OR 2.84, 95% CI 2.78-2.89), diabetes with complications (OR 1.27, 95% CI 1.24-1.29), and drug abuse (OR 1.27, 95% CI 1.22-1.31) that increased the likelihood of AMI-related hospitalization. The utilization rate of surgical treatment (PCI) was 14.37% for the management of AMI in inpatients with pneumonia. Inpatients co-diagnosed with pneumonia and comorbidities such as hypertension and diabetes were more likely to be hospitalized for AMI. These at-risk patients should be considered for early risk stratification. Utilization of PCI was associated with a lower in-hospital mortality rate.

Duodenal Adenocarcinoma in a patient with Lynch Syndrome. A Case Report and Facts Related to Small Intestine Cancer

Diagnosing small bowel cancer has been challenging due to its unusual presentation and inaccessibility on endoscopy. A 41-year-old male with a history of irritable bowel syndrome underwent esophagogastroduodenoscopy (EGD) for worsening fatigue and lightheadedness despite iron supplements therapy for low hemoglobin. Initial upper endoscopy showed esophagitis and non-bleeding duodenal bulb ulcer with exudate. Endoscopic ultrasound (EUS) with fine-needle aspiration was done due to persistent concern of malignancy and demonstrated moderately differentiated adenocarcinoma in the second portion of the duodenum. Endoscopic ultrasound with fine-needle aspiration may be a superior approach to diagnosing duodenal carcinoma than EGD alone. Small bowel cancer can be a part of the tumor spectrum of Lynch syndrome. Duodenal adenocarcinomas present at a late stage and portend a poor prognosis. We present a case of duodenal adenocarcinoma in an otherwise healthy individual emphasizing the importance of malignancy in the differential and genetic counseling in individuals with the family risk factor.

Abstract 229: Burden And Predictors Of Sepsis-associated Cardiac Arrest: A National Inpatient Sample Analysis, 2018

Background: Sepsis-induced myocardial dysfunction with the resultant cardiomyopathy carries a high risk of mortality. We aimed to study the risk factors of cardiac arrest (CA) in Sepsis-related hospitalizations (SRH).

Methods: We identified SRHs using the National Inpatient Sample (2018) and ICD10 codes to categorized them into with vs without CA. We then compared baseline characteristics and performed multivariate analysis adjusting for confounders to identify predictors of sepsis-associated CA.

Results: Of SRH (1,345,595) in 2018, 0.8% (11,365) had a CA (Table1) . SRH with CA often had elderly (median age 70 vs 66 years), males (55.3% vs 48.8%), blacks (19.6% vs 13.3%), Hispanics (12.3 vs 11.7%), Medicare enrollees (69.9 vs 59.1%), and had patients from lower-income households (LIH, 36.9% vs 30.7%) than non-CA cohort. Statistically significant predictors for CA in SRH were age (5% increased risk every 5 years), male sex (aOR 1.28, 95CI 1.16-1.4), black (aOR 1.49, 95CI 1.3-1.7) & Hispanic (aOR 1.26, 95CI 1.09-1.45) race, LIH (aOR 1.31, 95CI 1.13-1.52), CHF (aOR 2.4, 95CI 2.16-2.68), pulmonary circulation disorder (aOR 2.14, 95CI 1.72-2.66), prior cardiac arrest (aOR 1.95, 95CI 1.16-3.27), coagulopathy (aOR 1.69, 95CI 1.5-1.9), alcohol abuse (aOR 1.42 95CI 1.17-1.74), PVD (aOR 1.36, 95CI 1.17-1.58), CKD (aOR 1.26, 95CI 1.14-1.39), cancer without metastasis (aOR 1.49, 95CI 1.24-1.8) and with metastasis (aOR 1.24, 95CI 1.01-1.52). Urban non-teaching vs rural (aOR 1.32, 95CI 1.1-1.57) and Southern vs Northeast hospitals (aOR 1.26, 95CI 1.09-1.46) showed higher odds of CA.

Conclusion: SRH associated CA had high mortality with prevalent demographic and regional disparities, evident from black and Hispanic, males, patients from LHI and Southern hospitals revealing a higher risk of sepsis-associated CA. Congestive heart failure, pulmonary disease, prior cardiac arrest, coagulopathy, alcohol abuse, PVD, CKD, and cancers were the strongest predictors of CA in SRH.

Abstract 230: Prediabetes In Young Adults And Its Association With Type 1 Myocardial Infarction-related Admissions And Outcomes: A Population-based Analysis In The United States

Background: Prediabetes (pDM) has recently drawn attention for being associated with poor outcomes after acute myocardial infarction (MI). We aimed to analyze the incidence and odds of type 1 MI admissions, and outcomes using a nationally representative sample.

Methods: We queried the National Inpatient Sample (2018) to identify T1MI-related hospitalizations (T1RH) in young (18-44 years) adults with vs without pDM using ICD-10 codes. T1RHs with DM were excluded. Demographics, comorbidities and outcomes including major cardiovascular and cerebrovascular adverse events (MACCE) were compared between two cohorts.

Results: Overall prevalence of pDM in young adults hospitalized in 2018 was 0.4% (31460/7851019). T1RH was found to be significantly higher in the pDM vs. non-pDM cohort (2.15%, 675/31460 vs. 0.3%, 21655/7820953) among all non-diabetic admissions in young adults. T1RH with pDM often had males (78.5 vs 72.8%), blacks (26.7 vs 21%), Hispanics (18.3 vs 11.5%), Asian/Pacific Islanders (6.9 vs 3.1%), patients from higher-income quartile (19.1 vs 15.8%), urban-teaching (81.5 vs 72.2%), Midwest (23.7 vs 21.9%) and West (23 vs 16.4%) region hospitals, and patients with higher rates of hyperlipidemia (68.1 vs 47.3%), obesity (48.9 vs 25.7%), fluid-electrolyte imbalance (18.5 vs 15.3%). The univariate (OR 7.9, 95CI 6.54-9.53) and adjusted multivariate analysis (OR 1.71, 95CI 1.38-2.12) revealed significantly higher odds of T1MI in the pDM vs non-pDM cohort (p<0.001) [Table 1] . However, T1RH’s outcome for MACCE (adjusted) did not differ between two cohorts (P=0.074). Furthermore, T1RH with pDM had higher transfers to short-term facilities (6.7 vs 5.3%, p<0.001).

Conclusion: Young patients with prediabetes had significantly higher T1MI hospitalizations without any impact on subsequent MACCEs. This highlights the need for aggressive management of CVD risk factors in the young by primary care physicians to curtail acute cardiac events and healthcare costs.

P2806A novel sirolimus drug eluting stent for Small-Vessel Disease: results from en-ABL e-registry

Objective

The aim of the study was to assess the clinical outcome of Abluminus DES in patients with small vessels.

Background

Percutaneous coronary intervention (PCI) of small coronary vessel (≤2.75 mm) associated with more chances of restenosis and repeat revascularization even when drug eluting stent employed.

Methods

A total of 2,500 patients enrolled in en-ABL e-registry which is a prospective, multicentre observational post market registry. Out of 2,500 patients, 1,253 patients had small vessel (SV, ≤2.75 mm) while 1,247 had large vessel (LV, >3mm) disease. The primary endpoint was major adverse cardiac events (MACE) which is composite of cardiac death, target vessel myocardial infraction (TV-MI) and target lesion/vessel revascularization (TLR) at 1 year follow up. The secondary endpoint were stent thrombosis and MACE up to 2 years.

Results

Baseline characteristics were well matched in both groups. In the SV group had higher prevalence of diabetes as compared to large vessel 43.0% vs 25.7%. Total 1,400 lesions treated with 1,612 Abluminus DES and 1,569 lesions treated with 1,675 Abluminus DES in SV and LV groups respectively. The mean diameter of stent was 2.61±0.23 and 3.3±0.3 mm in SV and LV groups respectively. There was a significant difference in MACE in treatment groups (3.7% vs. 1.4%, p=0.004 respectively) at 1 year. No significant differences were observed between SV and LV groups in terms of death/myocardial infarction or stent thrombosis. There were increment of only one TLR and no stent thrombosis reported at 2-year follow-up.

Conclusion

This result suggests the efficacy and safety of novel Abluminus DES in small vessel disease.

Elemental geochemistry of sedimentary rocks at Yellowknife Bay, Gale crater, Mars

Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.

In situ radiometric and exposure age dating of the martian surface

We determined radiogenic and cosmogenic noble gases in a mudstone on the floor of Gale Crater. A K-Ar age of 4.21 ± 0.35 billion years represents a mixture of detrital and authigenic components and confirms the expected antiquity of rocks comprising the crater rim. Cosmic-ray-produced (3)He, (21)Ne, and (36)Ar yield concordant surface exposure ages of 78 ± 30 million years. Surface exposure occurred mainly in the present geomorphic setting rather than during primary erosion and transport. Our observations are consistent with mudstone deposition shortly after the Gale impact or possibly in a later event of rapid erosion and deposition. The mudstone remained buried until recent exposure by wind-driven scarp retreat. Sedimentary rocks exposed by this mechanism may thus offer the best potential for organic biomarker preservation against destruction by cosmic radiation.

Mechanical properties of the human cervical spine as shown by three-dimensional load-displacement curves

STUDY DESIGN

The mechanical properties of multilevel human cervical spines were investigated by applying pure rotational moments to each specimen and measuring multidirectional intervertebral motions.

OBJECTIVES

To document intervertebral main and coupled motions of the cervical spine in the form of load-displacement curves.

SUMMARY OF BACKGROUND DATA

Although a number of in vivo and in vitro studies have attempted to delineate normal movement patterns of the cervical spine, none has explored the complexity of the whole cervical spine as a three-dimensional structure.

METHODS

Sixteen human cadaveric specimens (C0-C7) were used for this study. Pure rotational moments of flexion-extension, bilateral axial torque, and bilateral lateral bending were applied using a specially designed loading fixture. The resulting intervertebral motions were recorded using stereophotogrammetry and depicted as a series of load-displacement curves.

RESULTS

The resulting load-displacement curves were found to be nonlinear, and both rotation and translation motions were coupled with main motions. With flexion-extension moment loading, the greatest degree of flexion occurred at C1-C2 (12.3 degrees), whereas the greatest degree of extension was observed at C0-C1 (20.2 degrees). With axial moment loading, rotation at C1-C2 was the largest recorded (56.7 degrees). With lateral bending moments, the average range of motion for all vertebral levels was 7.9 degrees.

CONCLUSIONS

The findings of the present study are relevant to the clinical practice of examining motions of the cervical spine in three dimensions and to the understanding of spinal trauma and degenerative diseases.

Phacoemulsification in Indian eyes with pseudoexfoliation syndrome

PURPOSE

To evaluate the intraoperative and postoperative behavior after phacoemulsification in Indian eyes with pseudoexfoliation syndrome.

SETTING

Iladevi Cataract & Intraocular Lens Research Centre, Ahmedabad, India.

METHOD

Ninety eyes were prospectively evaluated. Group 1 (cohort) comprised 45 consecutive eyes with pseudoexfoliation and coexisting cataract and Group 2 (control), 45 consecutive normal eyes with senile cataract only. Phacoemulsification was performed by a single surgeon using a step-by-step, chop in situ, and lateral separation technique. An AcrySof intraocular lens was implanted in the bag in all eyes. Intraoperative observations included pupil size after maximal mydriasis, phakodonesis, zonular dehiscence, grade of cataract, and capsule tear/rupture. Postoperatively, intraocular pressure (IOP), best corrected visual acuity, aqueous flare/cell response, and the presence of posterior synechias were evaluated at 1 day and 1 month. A chi-square test was used for statistical analyses.

RESULTS

The mean pupil size was significantly smaller in Group 1 (P =.0000). No eye in either group had phakodonesis. Sixty percent of eyes in Group 1 and 31% in Group 2 had a hard cataract (P =.008). Endocapsular phacoemulsification was performed in 82% of eyes in Group 1 and 84% of eyes in Group 2. Intraoperative complications such as zonular or capsular dehiscence were not seen in any eye. Postoperatively, IOP and aqueous cell response were comparable between groups (P =.11 and P = 0.81, respectively). A significantly higher flare response was observed in Group 1 (P =.000). The visual outcome at 1 month was similar between groups.

CONCLUSIONS

The intraoperative performance of Indian eyes with pseudoexfoliation was comparable to that in normal eyes. A good surgical outcome is ensured by using an appropriate surgical technique. Apart from a higher flare response, the postoperative outcomes in eyes with pseudoexfoliation were within normal limits, and the outcome at 1 month was satisfactory.

Phacoemulsification in eyes with a small pupil

PURPOSE

To evaluate the intraoperative difficulties and long-term outcome of phacoemulsification through a small pupil using minimal iris manipulation.

SETTINGS

Iladevi Cataract & IOL Research Centre, Ahmedabad, India.

METHODS

This prospective study included 30 consecutive eyes with a maximally dilated pupil size of 4.0 mm or smaller. Except synechiolysis and occasional pupil retraction with a chopper, no iris manipulation was performed. The phacoemulsification technique included creation of deep central space, use of a low aspiration flow rate with appropriate vacuum, and step-by-step chop in situ and lateral separation of the nucleus. Patients were examined 1 day, 1 week, 1 and 3 months, and 1 year postoperatively. Specular microscopy was performed at 1 month and 1 year.

RESULTS

Fourteen eyes had chronic iritis, 12 had glaucoma surgery, 2 had pseudoexfoliation, and 2 had a rigid pupil. Mean follow-up was 13.6 months. Eighteen eyes (60%) had hard cataract. Mean preoperative pupil size was 2.80 mm +/- 0.75 (SD). Mean pupil size before the capsulorhexis was initiated was 4.42 +/- 0.58 mm. The iris was bruised in 10 eyes during cortex removal. Trace amounts of cortex were left in 4 cases. Two eyes had increased intraocular pressure in the early postoperative period. Six patients had a minimal amount of retained viscoelastic material (pseudofibrin), and 2 patients developed a sterile hypopyon. Sixteen eyes had cell deposits on the IOL surface and 12 eyes, fine uveal pigments. In 2 eyes with previous glaucoma surgery and in all eyes with iritis except 2, posterior synechias reformed.

CONCLUSIONS

Successful phacoemulsification was done with minimal or no pupil-widening maneuvers, restoring the preoperative pupil configuration.

Surgical techniques for difficult cataracts

This article reviews some of the advances that have taken place in the surgical techniques for difficult cataracts such as rock-hard, white, and posterior polar cataracts. Fashioning a central space, modified chopping maneuvers, and creation of multiple small fragments have enabled the surgeon to consistently achieve a successful outcome. A judicious combination of chop and separation movement in a step-by-step manner reduce the stress of the procedure and make it safer. Raised intracapsular pressure and poor visibility are dealt with through various innovative techniques. Use of high-viscosity sodium hyaluronate and double capsulorhexis allow the surgeon to achieve capsulorhexis with a high success rate. A controlled and gentle approach to phacoemulsification has proven to be the key factor for success in posterior polar cataracts.

Phacoemulsification in eyes with posterior polar cataract

PURPOSE

To evaluate the results of phacoemulsification in eyes with posterior polar developmental cataract and to appraise the strategy for surgical management.

SETTING

Iladevi Cataract & IOL Research Centre, Raghudeep Eye Clinic, Ahmedabad, India.

METHOD

This prospective study comprised 25 consecutive patients. All surgeries were performed by 1 surgeon. Endophacoemulsification was carried out after hydrodelineation. Hydrodissection or rotation was not attempted. A 2-port vitrectomy was performed when necessary.

RESULTS

Mean follow-up was 13.72 months (range 7 to 22 months). Nine patients (36%) developed posterior capsule rupture and 8 (32%) revealed plaques. An intraocular lens (IOL) was implanted in all 25 eyes. In 8 of 9 cases with rupture, the haptics were placed in the sulcus; in 1 case, the IOL was placed in the bag. One patient in the capsular rupture group developed macular edema 3 weeks postoperatively that responded to conservative treatment. Among 25 patients, 18 had a visual acuity of 20/20 to 20/30 and 6, 20/80 to 20/120. These 6 patients had residual posterior capsule plaque. All except 2 patients with plaque required a neodymium:YAG capsulotomy. In these patients, visual acuity improved to 20/30. In 1 patient, with microcornea, acuity did not improve to beyond 20/120.

CONCLUSION

This study confirms the predisposition to posterior capsule rupture in eyes with posterior polar cataracts. Careful surgical planning produces satisfactory technical and visual outcomes.

Graded thoracolumbar spinal injuries: development of multidirectional instability

Injuries of the thoracolumbar spine are serious, disabling, and costly to society. These injuries vary from mild ligament tears to severe bony fractures. Increased range of motion (ROM) and neutral zone (NZ) have been suggested as indicators of the resulting clinical instability. The purpose of the present study was to investigate the relative sensitivities and merits of the ROM and NZ in relation to spinal injuries of the thoracolumbar junction. A graded spinal trauma experiment was designed, in which the threshold of injury and injury progression were examined. Ten thoracolumbar human spine specimens (T11-L1) were traumatized using a high-speed incremental trauma model. The ROM and NZ, which indicate altered mechanical properties, were determined for three physiological motions: flexion/extension (FE), lateral bending (LB), and axial rotation (AR). The injury threshold was found to be 84 J (or 84 Nm) by examining both ROM and NZ for all motion types (P < 0.05), but the NZ was more sensitive. At the injury threshold, the NZ showed an overall average increase of 566% above that of the intact, while the equivalent increase in the ROM was only 94%. The NZ was also a more sensitive parameter documenting the progression of the injury beyond the injury threshold. After the maximum trauma of 137 J, the NZs for the three motions (FE, LB, and AR) increased by 700%, 1700%, and 3000% above their respective intact values. Corresponding increases in the ROM were much smaller: 115%, 184%, and 425% respectively. Direct extrapolation of the in vitro experimental findings to the clinical situation, as always, should be done with care. Our findings, however, suggest that the ROM, as measured from functional radiographs of a traumatized patient, may underestimate the true injury to the spinal column.

Relationship between lens and capsular bag size

PURPOSE

To measure the size of the lens and the empty capsular bag and evaluate the relationship between them.

SETTING

Iladevi Cataract & IOL Research Centre, Ahmedabad, India.

METHODS

In 46 eye-bank eyes, the equatorial diameter of the lens was measured after a corneoscleral button and the iris were removed. Empty capsular bag diameter was measured after extracapsular cataract extraction through an intact capsulorhexis.

RESULTS

Mean lens size was 10.20 mm +/- 0.38 (SD) and mean capsular bag size, 10.38 +/- 0.35 mm. The difference between the size of the lens and that of the empty capsular bag varied from 0 to 0.50 mm (mean 0.20 +/- 0.17 mm). Lenses measuring less than 10.25 mm in diameter showed an increase of 0.25 mm while lenses larger than 10.25 mm showed an increase of 0.09 mm.

CONCLUSION

Lens size was larger in our population than in previous studies. The increase in the empty capsular bag size was related to initial lens size.

Phacoemulsification of white mature cataracts

PURPOSE

To evaluate the intraoperative difficulties associated with phacoemulsification of white mature cataracts and develop a strategy for consistently achieving continuous curvilinear capsulorhexis (CCC) in these cases.

SETTING

Raghudeep Eye Clinic, Iladevi Cataract & IOL Research Centre, Ahmedabad, India.

METHODS

This prospective study comprised 60 eyes of 60 patients with senile white mature cataract. Mean follow-up was 7 months. Detailed preoperative and intraoperative notes were made including intraoperative subjective assessment of the intracapsular pressure and cataract hardness. A small capsulorhexis was attempted initially. Endophacoemulsification was performed using the stop, chop, chop, and stuff technique. The capsulorhexis was enlarged before intraocular lens implantation. An initial cut in the capsulorhexis margin was made with a cystotome needle while a spatula supported the anterior capsule. The capsulorhexis was then enlarged with forceps.

RESULTS

A CCC was achieved in 57 eyes (95%). Intracapsular pressure was judged to be raised in 24 eyes (40%). Of these, CCC was accomplished in 21 eyes (88%). Statistical analysis confirmed that raised intracapsular pressure was a significant factor. Capsule opacification or plaque was detected at the end of the surgery in 20 eyes (33%); 50% of the nuclei were of grade 5 hardness.

CONCLUSION

If a CCC can be achieved, the results of white cataract phacoemulsification are comparable to those of routine cataract surgery. When using the two-stage technique, one should be prepared to deal with a hard cataract through a small capsulorhexis.

Functional morphology of the spinal canal after endplate, wedge, and burst fractures

Changes in the canal diameter during physiological motions are important considerations in the treatment of patients who have a burst fracture with the presence of bony fragments, but without neurologic deficit. In this in vitro study, the changes in the soft-canal diameter of the thoracolumbar region, when intact and after different fractures, was investigated under several different loading conditions. The soft-canal diameter was clearly identified on the lateral radiographs by attaching a series of steel balls to the posterior longitudinal ligament and ligamentum flavum in the midsagittal plane. Endplate, wedge, and burst fractures were produced incrementally in 19 three-vertebrae human cadaveric spine specimens by high-speed impacts. After each injury, a series of functional lateral radiographs were taken. The minimal canal diameter (MCD) was obtained by digitizing the images of the steel balls on radiographs using a custom-designed computer program. In the intact specimens, the MCD at the disc level changed significantly in flexion, extension, and compression, when compared with the MCD in the unloaded neutral position. However, the changes were small. The MCD after endplate and wedge fractures changed in a similar way. However, after the burst fracture, the MCD at the bone fragment level increased remarkably by a distraction force. It also significantly improved by an anterior shear force in comparison to the corresponding MCD in the neutral position. However, this change was smaller than the change due to the distraction force.

Enlarging the capsulorhexis

We describe a method to enlarge an initial small capsulorhexis using an iris spatula and cystotome needle. The iris spatula is placed underneath the anterior capsulorhexis margin; the spatula supports the anterior capsule and protects the posterior capsule. A gentle touch on the spatula by the cystotome needle generates a break in the continuity. This is done prior to intraocular lens implantation with the capsular bag and anterior chamber filled with viscoelastic.

Primary posterior capsulorhexis with and without anterior vitrectomy in congenital cataracts

PURPOSE

To determine whether anterior vitrectomy is necessary along with primary posterior capsulorhexis in children less than 5 years of age with congenital cataracts.

SETTING

Iladevi Cataract & IOL Research Centre, Ahmedabad, India.

METHOD

This prospective study comprised 18 eyes of 16 children whose mean age was 2.3 years (range 3 months to 5 years). Primary posterior continuous curvilinear capsulorhexis (PCCC) and posterior chamber intraocular lens (IOL) implantation were performed in all eyes. No vitrectomy was done in 8 eyes (Group 1); an anterior vitrectomy was performed in 10 eyes (Group 2). Optic capture through the posterior capsule was achieved in 3 eyes in Group 1 and in 5 eyes in Group 2. Average follow-up was 13.3 months.

RESULTS

Five eyes (62.5%) in Group 1 needed secondary pars plana vitrectomy because the visual axis was obscured; no eye in Group 2 needed a secondary procedure. Four Group 1 eyes developed significant complications (updrawn pupil, decentration, occlusio pupillae, transient glaucoma). While no Group 2 eye developed a serious complication, some degree of pigment dispersion was noted in all the eyes.

CONCLUSION

The results suggest that anterior vitrectomy is desirable along with primary PCCC in children younger than 5 years with congenital cataracts.

Capsulorhexis: its safe limits

We undertook this study to determine the safe limits of capsulorhexis during nucleus expression in 40 eyes of patients undergoing extracapsular cataract extraction (ECCE) with a posterior chamber intraocular lens (PCIOL) implantation and in 30 cadaver eyes. In group I (patient eyes), capsulorhexis of 4.5 to 7.5 mm was performed and the nucleus was expressed by hydrodissection. The nuclei measured 4.5 to 9.0 mm. One relaxing incision at 12 o'clock position had to be placed in 9 patients. In group II (cadaver eyes), continuous curvilinear capsulotomies of 4.0, 4.5, 5.0, 5.5, 6.0 and 6.5 mm were made in 5 eyes each. No relaxing incisions were placed. In both the groups, nuclei of all sizes could be safely delivered through intact capsulotomies measuring 5.5 mm or more. In two patient eyes, posterior capsule rupture occurred with rhexis measuring 4.5 and 5.0 mm, respectively. In the cadaver eyes, intracapsular extraction occurred in 4 eyes with rhexis measuring 5.0 mm or less. We conclude that a rhexis less than 5.5 mm is not safe for nucleus delivery during ECCE.

Dynamic canal encroachment during thoracolumbar burst fractures

In the burst fractures seen clinically, often poor correlation exists between the neurological deficit and the canal encroachment measured on post-trauma radiographic images. The purpose of the present study was to determine whether the dynamic canal encroachment during the trauma is greater than the static canal encroachment posttrauma. We successfully produced burst fractures in nine of 15 fresh human cadaveric thoracolumbar spine specimens (T11-L1). The specimens were incrementally impacted in a high-speed trauma apparatus until fracture occurred. During the trauma, dynamic canal encroachments were measured using three specially designed transducers placed in the canal at the levels of the superior end-plates of the T12 and L1 and the T12/L1 disk. After the trauma, residual static spinal canal encroachments were measured from the radiographs of the specimens that were prepared with 1.6-mm diameter steel balls lining the canal in the midsagittal plane. We found that the average canal diameter was 16.6 +/- 1.3 mm and the static canal encroachment was 18.0% of the canal diameter. The corresponding dynamic canal encroachment was 33.3%. Thus, the dynamic canal encroachment was 85% more than the static measurement. The clinical significance of this study lies in providing awareness to the clinician that the dynamic canal encroachment is significantly greater than the static canal encroachment seen on posttrauma radiographs or computed tomography scans. The finding may also explain the clinical observation of poor correlation between the canal encroachment measured radiographically and the neurological deficit.

On the understanding of clinical instability

STUDY DESIGN

Three-dimensional flexibility changes due to the application of an external fixator at C4-C5 were studied in cervical spine specimens.

OBJECTIVES

To evaluate the biomechanical effects of applying a cervical external fixator to a patient using an in vitro model.

SUMMARY OF BACKGROUND DATA

There is controversy regarding the relationship between the changes in spinal motion and clinical instability.

METHODS

Using fresh cadaveric C4-C7 specimens, multidirectional flexibility was measured at all vertebral levels, before and after the fixator application at C4-C5, C5-C6, and C4-C6.

RESULTS

The average ranges of motion for flexion, extension, lateral bending, and axial rotation were 8.3 degrees, 7.2 degrees, 5.3 degrees, and 5.6 degrees, which decreased by 40%, 27%, 32%, and 58%, respectively, because of the fixator application. The corresponding neutral zones were 3.4 degrees, 3.4 degrees, 3.0 degrees, and 2.0 degrees, which decreased by 76%, 76%, 54% and 69%, respectively. The decreases with the fixation at C4-C5 were similar to those for fixation at C5-C6.

CONCLUSIONS

This in vitro study documented that the application of an external fixator to the cervical spine decreases the intervertebral motion in general, and decreases flexion, extension and torsional neutral zones in particular. The findings help explain the clinical instability of the spine and support the hypothesis that the neutral zone is more closely associated with the clinical instability than is the range of motion.

Intraocular lens implantation in infants with congenital cataracts

We evaluated 21 eyes of 13 infants between two and eight months old who had primary posterior chamber intraocular lens (IOL) implantation for congenital cataracts between 1988 and 1993. Twelve eyes had a posterior capsulorhexis or plaque peeling at the time of implantation and one eye had a vitrectomy. Eight eyes had no posterior capsule procedure during the initial surgery. Follow-up ranged from six months to five years. All eyes developed one or multiple posterior synechias and all, except one, required secondary capsulectomy and vitrectomy between one month and one year. Twenty eyes attained stable IOL fixation and a clear visual axis. In one eye, the IOL decentered downward. Patients with bilateral cataracts had greater visual improvement than those with a cataract in one eye only. No patient could manage spectacles postoperatively. Our findings show the benefits of posterior capsulectomy and anterior vitrectomy done in the early postoperative period and that IOL implantation in infants is a reasonable treatment in some parts of the world.

[The unstable spine--an "in vitro" and "in vivo study" on better understanding of clinical instability]

In cases of suspected painful instability of a cervical segment, temporary external fixation by means of external fixator was applied. The segmental immobilization caused immediate relief of pain. The pain reoccurred after removal of the immobilization. The effect of immobilization by external fixation was investigated in biomechanical tests using fresh cadaveric C4-7 specimens. Multidirectional flexibility was measured before and after application of the fixator at C4/C5, C5/C6 and C4-6. We measured the reduction in motion between the different segments. In every situation the neutral zone decreased more than the range of motion. The findings are helpful to understand the clinical instability of the spine and support the hypothesis that the neutral zone is more closely associated with clinical instability than range of motion. The combination of clinical application and biomechanical investigation allowed us to establish a direct correlation between instability and pain.

Disc degeneration affects the multidirectional flexibility of the lumbar spine

STUDY DESIGN

An in vitro biomechanical investigation using human lumbar cadaveric spine specimens was undertaken to determine any relationship between intervertebral disc degeneration and nonlinear multidirectional spinal flexibility.

SUMMARY OF BACKGROUND DATA

Previous clinical and biomechanical studies have not established conclusively such a relationship.

METHODS

Forty-seven discs from 12 whole lumbar spine specimens were studied under the application of flexion-extension, axial rotation, and lateral bending pure moments. Three flexibility parameters were defined (neutral zone (NZ), range of motion (ROM), and neutral zone ratio (NZR = NZ/ROM)) and correlated with the macroscopic and radiographic degeneration.

RESULTS AND CONCLUSIONS

In flexion-extension, the ROM decreased and NZR increased with degeneration. In axial rotation, NZ and NZR increased with degeneration. In lateral bending, the ROM significantly decreased and the NZR increased with degeneration. In all three loading directions, the NZR increased, indicating greater joint laxity with degeneration.

Anular incision technique on the strength and multidirectional flexibility of the healing intervertebral disc

STUDY DESIGN

This study used a sheep model to biomechanically analyze the healing strength of the anulus fibrosus after two types of anular incisions.

OBJECTIVE

This study evaluated whether the type of anular incision made at the time of lumbar discectomy plays a role in the subsequent healing strength of the anulus and the biomechanical flexibility of the corresponding motion segment.

METHODS

Two types of anular incision, a full thickness removal of a box or window of anulus and a full thickness straight transverse slit through the anulus, were made in the intervertebral discs of 18 adult sheep. After healing times of 2, 4, and 6 weeks, the intervertebral discs were tested versus control levels for strength of anular healing and biomechanical flexibility of the corresponding motion segment.

RESULTS

The box incised discs showed a significantly greater loss in strength during the early healing phase (2 to 4 weeks) and a longer response before recovering anular strength when compared with the slit-incised discs. The type of incision also affected the multidirectional flexibility of the motion segments in a differentiated manner. Larger amounts of motion were seen with the box incision when compared with the slit incision at all time periods and in all pure moments.

CONCLUSION

The technique of anular incision plays a definite role in the timing and strength of subsequent anular healing. The box incision through the anulus led to significantly weaker healing than did the slit incision in the early healing phase (2-4 weeks). Also, larger amounts of motion were seen in the vertebral motion segments of those discs undergoing box incision when compared with slit or control levels.

Kinematics of the cervical spine canal: changes with sagittal plane loads

Spondylotic myelopathy is a result of decreased spinal canal space due to degeneration. The space also may change with physiological movements. The knowledge of the normal physiological changes is necessary for a better understanding of the clinical symptoms. Using a novel technique, we measured the changes in disk bulge, ligamentum flavum bulge, and anteroposterior canal diameter in response to tension-compression forces (up to 40 N each) and combined loading: 2 Nm of flexion or extension moment combined with 20 N compression force in five human cadaveric lower cervical spine specimens (C4-C7). From tension to compression, the average disk bulge changed 1.13 mm or 10.1% of the original canal diameter. The ligamentum flavum bulge changed 0.73 mm or 6.5% of the canal diameter. From flexion to extension the average disk bulb changed 1.16 mm or 10.8% of the canal diameter, whereas the ligamentum flavum bulge changed 2.68 mm or 24.3% of the canal diameter. Most of the changes in the bulges occurred with a small load application around the neutral position of the spine. The results of this study demonstrate that ligamentum flavum bulge can contribute significantly to canal encroachment in extension and that a flexed posture increases the sagittal diameter of the spinal canal.

Fermentation of a Yeast Producing A. Niger Glucose Oxidase: Scale-Up, Purification and Characterization of the Recombinant Enzyme

We have developed a fermentation process to produce up to 3 grams per liter of active, secreted glucose oxidase from a recombinant Saccharomyces cerevisiae. Real-time size-exclusion HPLC analysis is used to monitor enzyme production during fermentation, and purification to more than 95 percent is obtained using only filtration methods. The recombinant enzyme is stable to higher temperatures and a wider pH range than the native Aspergillus niger enzyme, and is free of contaminating amylase, cellulase and catalase.

Glucose oxidase from Aspergillus niger. Cloning, gene sequence, secretion from Saccharomyces cerevisiae and kinetic analysis of a yeast-derived enzyme

The gene for Aspergillus niger glucose oxidase (EC 1.1.3.4) has been cloned from both cDNA and genomic libraries using oligonucleotide probes derived from the amino acid sequences of peptide fragments of the enzyme. The mature enzyme consists of 583 amino acids and is preceded by a 22-amino acid presequence. No intervening sequences are found within the coding region. The enzyme contains 3 cysteine residues and 8 potential sites for N-linked glycosylation. The protein shows 26% identity with alcohol oxidase of Hansenuela polymorpha, and the N terminus has a sequence homologous with the AMP-binding region of other flavoenzymes such as p-hydroxybenzoate hydroxylase and glutathione reductase. Recombinant yeast expression plasmids have been constructed containing a hybrid yeast alcohol dehydrogenase II-glyceraldehyde-3-phosphate dehydrogenase promoter, either the yeast alpha-factor pheromone leader or the glucose oxidase presequence, and the mature glucose oxidase coding sequence. When transformed into yeast, these plasmids direct the synthesis and secretion of between 75 and 400 micrograms/ml of active glucose oxidase. Analysis of the yeast-derived enzymes shows that they are of comparable specific activity and have more extensive N-linked glycosylation than the A. niger protein.