A longitudinal assessment of sex differences in the growth of the mandibular retromolar space

OBJECTIVE

To assess longitudinal variation in patterns of retromolar space growth, with regard to sex and cervical vertebrae maturation.

DESIGN

We utilized serial lateral cephalograms from three craniofacial growth studies (Denver, Iowa, Oregon), measuring retromolar space and cervical vertebrae maturation in 99 subjects (56% male) from 8 to 18 years of age for each subject. Repeated measures ANOVA and a linear mixed effects model were used to assess retromolar space growth through time.

RESULTS

Our analyses revealed an average increase in retromolar space of 8.73 mm from 8 to 18 years. While t-tests failed to find differences in retromolar space growth between males and females at the measured age points, repeated measures ANOVA and linear mixed effects models revealed modest differences in growth trends between sexes, with females having more growth earlier but a younger age of deceleration of growth (between 12 and 14 years of age).

CONCLUSIONS

Our results confirm large increases in retromolar space through growth, reaching an average of 1.38 mm/year around puberty. Importantly, we add to the conversation regarding sex differences, showing differences in timing of growth. This highlights the importance of using longitudinal data and analytical approaches to address questions of this nature.

When Is Parenteral Nutrition Appropriate?

Parenteral nutrition (PN) represents one of the most notable achievements of modern medicine, serving as a therapeutic modality for all age groups across the healthcare continuum. PN offers a life-sustaining option when intestinal failure prevents adequate oral or enteral nutrition. However, providing nutrients by vein is an expensive form of nutrition support, and serious adverse events can occur. In an effort to provide clinical guidance regarding PN therapy, the Board of Directors of the American Society for Parenteral and Enteral Nutrition (ASPEN) convened a task force to develop consensus recommendations regarding appropriate PN use. The recommendations contained in this document aim to delineate appropriate PN use and promote clinical benefits while minimizing the risks associated with the therapy. These consensus recommendations build on previous ASPEN clinical guidelines and consensus recommendations for PN safety. They are intended to guide evidence-based decisions regarding appropriate PN use for organizations and individual professionals, including physicians, nurses, dietitians, pharmacists, and other clinicians involved in providing PN. They not only support decisions related to initiating and managing PN but also serve as a guide for developing quality monitoring tools for PN and for identifying areas for further research. Finally, the recommendations contained within the document are also designed to inform decisions made by additional stakeholders, such as policy makers and third-party payers, by providing current perspectives regarding the use of PN in a variety of healthcare settings.

Recurrent carcinoma after breast conservation: diagnosis with stereotaxic core biopsy

PURPOSE

To evaluate the utility of stereotaxic core biopsy (SCB) in diagnosing recurrent carcinoma after breast-conserving therapy (BCT).

MATERIALS AND METHODS

Of 316 patients evaluated with SCB, 17 (5%) had nonpalpable lesions in breasts previously treated with BCT. Surgical correlation was obtained in 14 patients. SCBs were performed with digital stereotaxic equipment, with patients prone.

RESULTS

Carcinoma detected at SCB in 11 (79%) of 14 patients included infiltrating ductal carcinoma (IFDC) in five, ductal carcinoma in situ (DCIS) in five, and infiltrating lobular carcinoma (ILC) in one. Surgical histopathologic findings agreed with core biopsy findings in 10 of these patients. In one patient with two SCB-proved foci of IFDC, one IFDC was identified at mastectomy. In two (14%) patients, SCB revealed atypical ductal hyperplasia; however, DCIS was found at surgical biopsy. In one patient, the SCB finding of fat necrosis was confirmed at surgical biopsy.

CONCLUSION

These data suggest that SCB may be useful in diagnosing recurrent carcinoma in the conservatively treated breast.

A human recombinant haemoglobin designed for use as a blood substitute

The need to develop a blood substitute is now urgent because of the increasing concern over blood-transmitted viral and bacterial pathogens. Cell-free haemoglobin solutions and human haemoglobin synthesized in Escherichia coli and Saccharomyces cerevisiae have been investigated as potential oxygen-carrying substitutes for red blood cells. But these haemoglobins cannot be used as a blood substitute because (1) the oxygen affinity in the absence of 2,3-bisphosphoglycerate is too high to allow unloading of enough oxygen in the tissues, and (2) they dissociate into alpha beta dimers that are cleared rapidly by renal filtration, which can result in long-term kidney damage. We have produced a human haemoglobin using an expression vector containing one gene encoding a mutant beta-globin with decreased oxygen affinity and one duplicated, tandemly fused alpha-globin gene. Fusion of the two alpha-globin subunits increases the half-life of this haemoglobin molecule in vivo by preventing its dissociation into alpha beta dimers and therefore also eliminates renal toxicity.

Synthesis of Wild Type and Mutant Human Hemoglobins in Saccharomyces cerevisiae

We have expressed human alpha and beta-globin cDNA clones from separate, synthetic galactose-regulated hybrid promoters contained on a single plasmid in Saccharomyces cerevisiae. Co-expression of the alpha and beta-globin chains in S. cerevisiae results in the assembly of these proteins into soluble tetrameric hemoglobin that accumulates to 3-5 percent of the total cell protein. Endogenously produced heme is incorporated into the tetramer and the protein produced is functionally and structurally indistinguishable from human Ao hemoglobin. This expression system has been used to produce both wild type hemoglobin and a low O2-affinity hemoglobin mutant that has oxygen binding and dissociation characteristics similar to human whole blood. The yeast expression system we describe may be suitable for the production of a recombinant hemoglobin based blood substitute as well as for detailed structure-activity studies of human hemoglobin.