Coupling the dynamics of diffused gases and microbial growth in modified atmosphere packaging.

Coupling microbial dynamics with the complete dynamics of the packaging gases is still a challenge. In this work the microbial growth kinetic parameters for Pseudomonas and Lactic Acid Bacteria (LAB) in MAP are identified based on accurate estimation of diffusivity of gases and parameter scaled sensitivity approaches. The microbial dynamics are also compared with those estimated based on partial pressure measurement. Scaled sensitivity coefficient analysis using dissolved gases as variable inputs, shows that in most cases the only coefficients large enough for estimation were those for CO2max-diss, and for µmax. The current data showed that dissolved gases led significant differences on the microbial parameter of CO2max values when compared with the headspace gases. On the other hand, the (so-called) dissolved specific growth rate follows a clear trend down for both microorganisms in relation to the increase of the initial headspace CO2. Finally, current results indicate a possible correlation between CO2max-diss, CO2max-headspace, and µmax as functions of CO2init.

Characterization of polyphenol oxidase from blueberry (Vaccinium corymbosum L.).

Polyphenol oxidase (PPO) was extracted and characterized from high-bush blueberries. PPO showed an optimum activity at pH 6.1-6.3 and 35°C, with the enzyme showing significant activity over a wide temperature range (25-60°C). Catechol was the most readily oxidized substrate followed by 4-methylcatechol, DL-DOPA, and dopamine. Blueberry PPO showed a Km of 15mM and Vmax of 2.57 ΔA420nm/min×10-1, determined with catechol. PPO was completely inactivated in 20min at 85°C, however, after 30minat 75°C it showed about 10% residual activity. Thermal treatment at 55 and 65°C for 30min resulted in the partial inactivation of PPO. Ascorbic acid, sodium diethyldithiocarbamic acid, L-cysteine, and sodium metabisulfite were effective inhibitors of PPO at 1.0mM. Benzoic acid and cinnamic acid series inhibitors showed relatively weak inhibition of PPO (21.8-27.6%), even at as high as 2.0mM concentration.

One-step global parameter estimation of kinetic inactivation parameters for Bacillus sporothermodurans spores under static and dynamic thermal processes.

Bacillus sporothermodurans produces highly heat-resistant endospores, that can survive under ultra-high temperature. High heat-resistant sporeforming bacteria are one of the main causes for spoilage and safety of low-acid foods. They can be used as indicators or surrogates to establish the minimum requirements for heat processes, but it is necessary to understand their thermal inactivation kinetics. The aim of the present work was to study the inactivation kinetics under both static and dynamic conditions in a vegetable soup. Ordinary least squares one-step regression and sequential procedures were applied for estimating these parameters. Results showed that multiple dynamic heating profiles, when analyzed simultaneously, can be used to accurately estimate the kinetic parameters while significantly reducing estimation errors and data collection.

A comparative study of contrast dacryocystogram and nuclear dacryocystogram.

A comparative study was run between conventional radiographic contrast dacryocystogram and radioisotope scan of the lacrimal drainage apparatus (henceforth called "nuclear dacryocystogram"). A total of 20 contrast dacryocystograms (DCG), 22 irrigations, and 42 nuclear dacryocystograms (DCG) were performed in 21 patients having symptoms of obstruction in the lacrimal drainage system. The study revealed that there was a good correlation between these two diagnostic techniques and nuclear DCG was, perhaps, superior to contrast DCG.

Evaluation of the pituitary. Patients with suspected prolactin-producing tumors.

We have reviewed our experience in the radiographic and ophthalmologic evaluation of 1001 patients with symptoms suggesting the presence of a pituitary, prolactin-secreting adenoma. Twenty-seven patients had abnormal or suspicious radiographic examination of the sella turcica. Twenty-two of those had hyperprolactinemia. In only one instance was an abnormality noted on polytomography that was not seen on a conventional four-view study of the skull. Based on these findings, a four-view plain conventional radiographic assessment of the skull suffices as a screening procedure in patients with amenorrhea, galactorrhea, or both. Thin section tomography should be reserved to more thoroughly evaluate those patients with elevated serum prolactin concentrations and/or abnormal conventional radiographs. We found visual field testing to be of little value as an initial screening procedure in these patients.

Paranasal sinus radiology, Part 3B: Sphenoidal sinus.

Mucoceles involving the sphenoidal sinus are not as common as those affecting the frontal and ethmoidal sinuses. The subtle expansile change produced by a sphenoidal sinus mucocele often requires conventional tomography or computed tomography examination to be detected. Similarly, involvement of surrounding structures by a sphenoidal mucocele may require special study, which this section illustrates. The sphenoidal enlargement and density change produced by fibrous dysplasia may mimic sinus disease. Focal or widespread bone destruction resulting from neoplastic involvement of the sphenoidal sinus requires special examination similar to that used with mucoceles.

Paranasal sinus radiology, Part 3A: sphenoidal sinus.

This article describes the complex anatomy of the sphenoid bone. The development and size of the sphenoidal sinuses are quite variable and complete analysis of the sinus walls requires several views. The essential plain film projections and use of tomography and CT scans are described. Sphenoidal sinus inflammatory disease produces changes similar to those already discussed in the articles in this series on the frontal sinus and the ethmoidal sinus. Illustrations of sphenoidal sinus inflammatory disease are provided.

Paranasal sinus radiology, Part 2B: ethmoidal sinuses.

The clinician must have a high level of suspicion in order to detect ethmoidal sinus disease. Survey plain film radiographic examination may provide information about gross changes in ethmoidal sinus transparency and the sinus walls. Conventional tomographic study will often aid evaluation of the ethmoidal sinus walls which may be obscured by overlying structures on plain films. Computerized tomography adds a new dimension to ethmoidal sinus study. By revealing not only bone changes but soft-tissue abnormality as well, more complete understanding of the disease process is gained. Computerized tomography is particularly useful in evaluating orbital structural change due to ethmoidal sinus abnormality.

Paranasal sinus radiology, Part 2A: Ethmoidal sinuses.

The clinician must have a high level of suspicion in order to detect ethmoidal sinus disease. Survey plain film radiographic examination may provide information about gross changes in ethmoidal sinus transparency and the sinus walls. Conventional tomographic study will often aid evaluation of the ethmoidal sinus walls which may be obscured by overlying structures on plain films. Computerized tomography adds a new dimension to ethmoidal sinus study. By revealing not only bone changes but soft-tissue abnormality as well, more complete understanding of the disease process is gained. Computerized tomography is particularly useful in evaluating orbital structural change due to ethmoidal sinus abnormality

Paranasal sinus radiology, part 1B: the frontal sinuses.

Alteration in the appearance of the mucosa, fluid accumulations, and change in the shape and texture of the sinus wall form the basis of the radiologic information that aids in the diagnosis of frontal sinus disease. Inflammatory disease of the frontal sinuses was discussed in Part 1A of this article; other disease processes of the frontal sinuses as they appear in the various roentgenographic modalities are described and illustrated here.

High resolution CT air cisternography in the diagnosis of small acoustic neuromas.

High resolution CT air cisternography was used to examine 38 patients with clinical findings and audiovestibular function studies consistent with a retrocochlear lesion. Four strictly intracanalicular lesions and 10 acoustic neuromas extending medially into the cerebellopontine angle (CPA) cistern by no more than 1 cm were detected and verified at surgery. There was one false-positive diagnosis produced by a tortuous inferior cerebellar artery branch. The contrast-enhanced axial scan was positive in only two patients. Both had extension of the tumor into the CPA by 1 cm. In these two cases the axial intravenous (IV) contrast-enhanced scan provided more information than the air CT. A patient with suspected acoustic neuroma is best examined initially with an IV contrast-enhanced axial scan followed by CT air cisternography where the contrast study is negative.

Paranasal sinus radiology, Part 4B: Maxillary sinuses.

The maxillary sinus is frequently involved by inflammatory change. It is also the sinus that is most often affected by intrinsic or neighboring neoplasms. Since neoplasia and inflammatory disease may mimic each other, radiologic examination often becomes the principal means of differentiating them. Principles of radiologic diagnosis, with attention to changes in the various bony margins in maxillary disease processes, form the basis of this article.

Paranasal sinus radiology, Part 4A: Maxillary sinuses.

The maxillary sinus is frequently involved by inflammatory change. It is also the sinus that is most affected by intrinsic or nearby neoplasms. Since neoplasia and inflammatory disease may mimic each other, radiologic examination often becomes the principal means of differentiating them. Principles of radiologic diagnosis, with attention to changes in the various bony margins in maxillary disease processes, form the basis of this article.

Air CT cisternography in the diagnosis of vascular loop causing vestibular nerve dysfunction.

Considerable interest has developed in otology concerning the relationship between the vascular loop and compression of the eighth nerve, producing vertigo. Several authors have described the radiographic findings relative to the anatomy of these vascular loops. Few previous articles have dealt with cases that have had surgical confirmation or repair of the defect. Our presentation concerns 27 patients who were studied by air CT cisternography of the cerebellopontine angle cistern and internal auditory canal followed by surgical repair. We postulate dampened pulsation as the reason for being able to visualize the vessels on the air study. The diversity of vessel-eighth nerve defects is illustrated. Compression of the vestibular nerve by a vascular loop should be considered one of the causes of intractable vertigo and motion intolerance and is a differential diagnosis in Meniere disease. Air CT cisternography is useful in diagnosing this condition in patients who do not respond to medical treatment.

Gadolinium-enhanced MR of the postoperative internal auditory canal following acoustic neuroma resection via the middle fossa approach.

PURPOSE: To evaluate the ability of gadolinium-enhanced MR in detecting recurrent tumor in patients whose acoustic neuromas were surgically removed via the middle cranial fossa approach. PATIENTS AND METHODS: Postoperative gadolinium-enhanced exams of 13 of 44 patients who underwent excision of acoustic neuromas via the middle cranial fossa approach were reviewed. RESULTS: Postoperative enhancement was seen in 12 of the 13 patients; two patients underwent serial exams without significant change. On the basis of a single exam, we were unable to conclusively differentiate postoperative enhancement from residual or recurrent tumor. CONCLUSIONS: A single exam is of limited value. Serial studies are recommended to identify changes that would indicate tumor growth. A proposed MR follow-up schedule is an initial baseline exam within 2 months of surgery and a repeat exam during the second postoperative year.

Developmental abnormalities of the cervical spine below the axis.

The majority of cervical spine anomalies of clinical significance occur in the occipital, atlas, and axis areas. Below the axis, changes may occur as local solitary anomalies simulating significant disease, or in the form of more widespread segmentation and ossification anomalies categorized as the Klippel-Feil syndrome.

Expanding lesions of the cervical spinal canal.

Attention has recently been directed to decrease in size of the spinal canal, notably in relation to production of posterior osteophytes in spondylosis. Tumors of the cord, roots, or meninges, syringolmyelia and hydromyelia may enlarge sufficiently in size or be critically located so that expansile change of the cervical spinal canal may result.

Cervicobasilar relationships.

It is prudent to apply several methods of evaluation of cervicobasilar relationships in basilar impression and, in suggestive cases, to use tomographic evaluation for complete study. This discussion reviews normal cervicobasilar relationships and illustrates selected pathologic processes that produce basilar impression.

Cervical spine injuries below the axis.

In the lower cervical spine, motion is relatively limited to flexion and extension, with a small amount of lateral flexion and rotation. Fractures may occur with extreme displacement in any of these directions or as a result of axial application of force. The author provides a guide for the radiologic detection of various fractures of the cervical vertebrae.

Correlative imaging of sphenoid dysplasia accompanying neurofibromatosis.

Experience with five cases of sphenoid dysplasia is collected and illustrated by plain film, computed tomography, and magnetic resonance imaging. Ancillary changes in the maxilla and mandible are shown. Paramount to the presentation are changes induced in the orbit resulting in a large superior orbital fissure with or without a meningeal cyst projecting through the fissure. Serial studies of one patient from birth through 5 years of age present the progressive nature of this abnormality.