Fragmentation of Therapeutic Human Immunoglobulin Preparations

Some commercial batches of human therapeutic immunoglobulins (Ig) have been found to show evidence of molecular fragmentation when examined by molecular sizing methodologies including sodium dodecyl sulphate polyacrylamide gel electrophoresis [SDS-PAGE] and size exclusion high performance liquid chromatography (SE-HPLC). These batches all demonstrated impaired immunobiological activity (efficacy) as assessed by Fc function measured using a rubella haemolytic assay and as such are likely to be subpotent for therapeutic use. Fragmented Igs were characterized by the presence of at least three protein bands and peaks additional to monomeric IgG. Incubation of Igs with blood enzymes (plasmin and kallikrein) reproduced the fragmentation patterns observed for intrinsically degraded batches, suggesting that fragmentation occurred by contamination with these proteases from the source material (human blood) during manufacture. Intravenous Igs (IVIG) were found to be more susceptible to proteolysis than intramuscular Igs, probably as a consequence of the post-fractionation processing that some IVIGs receive which may induce molecular alterations, allowing enzyme access and fragmentation. Two of the products examined were found to be relatively resistant to proteolysis and both were formulated by processes that limit enzyme activity. These processes were inclusion of an enzyme inhibitor, α₂-macroglobulin, and formulation at acidic pH. Enzyme carry-over into the final product is a likely cause of Ig fragmentation, and reduction in levels of such contamination should lead to improvements in product stability and efficacy.     

The endonasal approach to pituitary adenomas: experience in 105 procedures

OBJECTIVE: The endonasal approach to the sella turcica is supposed to simplify surgical techniques and reduce the risk and sequelae linked to removal of pituitary adenomas. We report our experience with 105 procedures using this approach. Method: The series included 45 men and 60 women, aged 17 to 83 years. Their intrasellar lesions were: 43 non-functional adnomas, 37 prolactinomas, 7 GH- adenomas, 9 corticotrop adenomas, 9 miscellaneous lesions (abscess, Rathke cleft cysts, empty sella). Mean duration of the procedures was 50 minutes. Mean hospital stay was 4 days. RESULTS: There were no deaths. Morbidity included: 1 (0.95%) rhinorrhea associated with meningitis which cured without sequelae, 11 (10.5%) transient diabetes insipidus lasting no longer than 48 hours, 2 cases of permanent diabetes insipidus (1 non-functional macroadenoma, 1 pituitary abscess), 1 transient hyposmia (3 months), 2 transient nasal obstructions. There were no cases of septal perforation, nasal deformation, partial or complete mucosal anesthesia, nasal pain, dental pain, or epistaxis. CONCLUSION: This surgical approach is easier to perform and causes less rhinological sequelae than the sublabial transsphenoidal approach. It allows an as effective tumor removal than the latter. Hospitalization stay is significantly shortened.     

Caregiving and multigenerational families.

This paper examines the possibility that the extension of traditional family household boundaries foreshadows an expanded caregiving system as family lines grow longer. An original study of 25 four-generation families, mapping all linear and lateral members, offers findings that confirm evidence found in a literature review. One primary caregiver, either a spouse or daughter, generally shoulders responsibility for members in adversity. A caregiving system encompassing more than two generations in direct descent was not discernible. Problems in caring for the oldest old are noted.     

Distribution, surface density, and membrane area of diadic junctional contacts between plasma membrane and terminal cisterns in mammalian ventricle.

The surface density of diadic junctional complexes (DJC) between plasmalemma and terminal cisternal membrane, as well as the areas of plasmalemmal and cisternal membrane involved in DJC, have been determined morphometrically in external plasmalemmal envelope and T-system of rabbit, rat, and mouse ventricular heart muscle. In all three species, both the surface density and the plasmalemmal area of DJC are 4- to 6-fold greater in the T-system than in the external plasmalemmal envelope. The surface density and DJC membrane area per unit cell volume and per unit myofibrillar volume increase in the order rabbit less than rat congruent to mouse and are not related simply to basal heart rate or intraventricular pressure. The results show that if Ca2+ release is a function of terminal cisterns, then, in ventricular heart muscle, most of the Ca2+ thus released for myofibrillar activation must originate from cisterns associated with the T-system. They make it necessary to consider the possibility that the 20--50% of plasmalemma in the T-system that is involved in excitation-contraction coupling may be unavailable for other processes; and they show that interspecies differences in surface density and membrane area of DJC/unit cellular and myofibrillar volume correlate with differences in Ca2+- activated Ca2+ release in skinned fibers and with differences in rate of tension development described for intact rat and rabbit ventricular muscle.     

The response to intravenous glucose infusion in normal and diabetic subjects

Summary Data from single injection studies on 23 normal subjects led to development of an intravenous primed — constant infusion test. The plasma glucose response to this test was determined in 48 normal and 24 diabetic subjects. Variation in plasma glucose concentration at equilibrium was minimal in normal and marked in diabetic subjects — assessed by the difference between maximum and minimum glucose concentration over the final 25 min of a 50 min infusion. This parameter was used successfully in predicting the course of 16 pregnant women with clinical suspicion of prediabetes unresolved by oral glucose tolerance tests.Submitted as part fulfillment of the requirements for Doctor of Medicine, Monash University, Melbourne, 1967.     

Angiotensinogen gene T235 variant: a marker for the development of persistent microalbuminuria in children and adolescents with type 1 diabetes mellitus

AIM: We examined genetic polymorphisms in the renin-angiotensin system (RAS) coding for angiotensin I-converting enzyme (ACE) insertion/deletion (I/D) for angiotensinogen (AGT) M235T and angiotensin II receptor type 1 (AGTR1) A1166C as predictors for the development of microalbuminuria (MA) in children with type 1 diabetes mellitus (T1DM). METHODS: Four hundred fifty-three (215 males, 238 females) T1DM children [median (interquartile range): age, 16.7 years (13.9-18.3); diabetes duration, 6.9 years (3.3-10.8); age at diagnosis, 9.1 years (5.8-11.8)] were followed prospectively from diagnosis until the development of MA (two of three consecutive overnight urine samples with albumin excretion rates of > or =20 and <200 microg/min). Kaplan-Meier survival curves and Cox proportional multivariate model estimated the probability of developing MA and the relative risk for MA among different variables. RESULTS: MA developed in 41 (9.1%) subjects. The frequencies of genotypes were as follows: ACE-II 112 (25%), ACE-ID 221 (49%), and ACE-DD 117 (26%) (n=450); AGT-MM 144 (32%), AGT-MT 231 (51%), and AGT-TT 77 (17%) (n=452); AGTR1-AA 211 (47%), AGTR1-AC 204 (45%), and AGTR1-CC 37 (8%) (n=452). The cumulative risk for the development of MA was higher in ACE-DD versus ACE-ID/II groups (log-rank test, P=.05), and a trend was noticed when AGT-TT was compared to AGT-MT/MM groups (log-rank test, P=.08). AGT-TT polymorphism conferred a fourfold increased risk for MA compared to AGT-MM/MT (hazard ratio=3.8; 95% confidence interval=1.43-10.3; P=.008). INTERPRETATION: Our findings suggest that RAS gene polymorphism at AGT M235T is a strong predictor for early MA in young T1DM subjects.     

Treatment of supraventricular tachycardias with transcatheter delivery of radiofrequency current.

Medical therapy for the treatment of supraventricular tachycardias is frequently ineffective and associated with significant side effects, whereas curative surgical approaches have generally been limited by their considerable morbidity and cost. Greater understanding of the mechanisms underlying supraventricular tachycardias has improved our ability to precisely map endocardial areas critical to arrhythmogenesis. Advances in catheter ablation techniques and particularly the use of radiofrequency current to generate thermal energy for ablation have resulted in dramatic success rates for curative catheter ablation. This review examines the physics of radiofrequency current ablation and its application to the treatment of atrial fibrillation, atrial flutter, AV nodal reentrant tachycardia, and arrhythmias associated with the Wolff-Parkinson-White syndrome. The limitations, risks, and cost-effectiveness of this technique relative to medical and surgical approaches are also evaluated.     

Inflammatory carcinoma of the breast. Clinical review and summary of the Vanderbilt experience with multi-modality therapy

Inflammatory breast cancer is a distinct clinicopathologic entity that accounts for 1 percent of all cases of breast cancer. The diagnosis should be strongly suspected on the basis of the distinctive clinical findings, which include edema of the breast, inflammation, wheals, and a typical reddish-purple color of the overlying skin. Pathologic examination usually shows infiltration of the dermal lymphatics with carcinoma. Evidence of distant metastatic spread is more frequent than with other types of breast cancer and is seen in approximately 30 percent of patients. The five-year disease-free survival rate is less than 5 percent when local therapy alone (mastectomy and/or local radiotherapy) is used. The addition of combination chemotherapy to high-dose local radiotherapy has improved the five-year survival rate to approximately 30 percent. The potential for long-term survival is limited to the subgroup of patients with only local-regional disease at the time of diagnosis. Patients with inflammatory breast cancer should be treated with combined-modality therapy using combination chemotherapy and high-dose radiotherapy to the breast, since this approach is potentially curative. The fatalism formerly associated with this diagnosis is no longer warranted, particularly in patients with local-regional disease. Failure to employ intensive combined-modality treatment will deny some patients a chance for long-term survival.     

A graphic framework for teaching critical appraisal of randomized controlled trials

Students of evidence-based medicine often try unsuccessfully to commit to memory a particular critical appraisal framework (often lengthy), or they have to depend on pocket cards and are lost without them. We have described a pedagogic aid: a flow diagram of an RCT, which has been developed over years of teaching residents. This diagram focuses on the steps in an RCT, and by drawing arrows, it highlights the biases possible at each step. This diagram serves as a framework on which the list of critical appraisal questions can be hung and is easy to remember.