"Pseudosarcoma" in a pregnant woman

Background

As a result of improvements in diagnostic accuracy, the primary source of the tumour is identified in more than 99% of cases presenting with a malignancy. Whilst the axial skeleton is a common site of metastases, the sternum is rarely affected, especially by isolated metastases.

Case presentation

We report a case of a 68 year old male who was referred to the surgical outpatient clinic with a six month history of sternal pain. The patient was known to have essential thrombocythaemia, which had recently transformed into acute myeloid leukaemia but a sternal biospy showed mucinous adenocarcinoma. He had not localising symptoms and full evaluation failed to localise the primary tumour.

Conclusion

Solitary sternal metastases are rare and when found an underlying neoplasm is usually identified allowing targeted treatment. If however, there is no symptomatic tumour, the metastasis should simply be treated symptomatically.     

A "microtubule" in a bacterium

A study of the anchorage of the flagella in swarmers of Proteus mirabilis led to the incidental observation of microtubules. These microtubules were found in thin sections and in whole mount preparations of cells from which most of the content had been released by osmotic shock before staining negatively with potassium phosphotungstate (PTA). The microtubules are in negatively stained preparations about 200 A wide, i.e. somewhat thicker than the flagella (approximately 130 A). They are thus somewhat thinner than most microtubules recorded for other cells. They are referred to as microtubules because of their smooth cylindrical wall, or cortex, surrounding a hollow core which is readily filled with PTA when stained negatively. Since this is probably the first time that such a structure is described inside a bacterium, we do not know for certain whether it represents a normal cell constituent or an abnormality, for instance of the type of "polysheaths" (16).     

"Craziness" and "visions": experiences after a stroke.

For a stroke victim there may be at least three types of strange occurrences: incorrect saying, seeing, and thinking. To the patient only the third seems to be "crazy". After a stroke (left hemisphere), which mainly produced serious aphasia, I (the patient) felt crazy two or three times when someone said something I expected him to say. On the other hand, my initial aphasic "gibberish speech" and an occasional false vision did not seem crazy. In my case the vision is always a car or a child, seen on my extreme right, where I am otherwise blind from the stroke. I am always driving when it happens; in recent years this phenomenon occurs when I am tired or tense, or the light is poor. These rapid visions do not seem insane but merely physical problems in my eyes, much like ordinary people''s dreams.     

"Reticular" and "Areticular" Nissl Bodies in Sympathetic Neurons of a Lizard

Sympathetic ganglia of the horned lizard, Phrynosoma cornutum, were fixed in OsO₄ and imbedded in methacrylate. Thin sections were cut for electron microscopy. Some adjacent thick sections were cut for light microscopy and were stained in acidified, dilute thionine both before and after digestion by RNase. In the light microscope two types of Nissl bodies are found, both removable by RNase: (1) a deep, diffuse, indistinctly bounded, metachromatic variety, and (2) a superficial, dense, sharply delimited, orthochromatic sort. Electron microscopically, the former ("reticular" Nissl bodies) corresponds to the granulated endoplasmic reticular structure of Nissl material previously described by others, whereas the latter ("areticular" Nissl bodies) comprises compact masses of particles of varying internal density and devoid of elements of endoplasmic reticulum. The constituent particles of the areticular Nissl material are 4 to 8 x the diameter of single ribonucleoprotein granules of the reticular Nissl substance and seem, near zones of junction with the reticular type, to arise by clustering of such granules with subsequent partial dispersion of the substance of the granules into an added, less dense material. It is suggested that the observed orthochromasia of the areticular Nissl substance is due to accumulation of a large amount of protein bound to RNA and, further, that these Nissl bodies may represent storage depots of RNA and protein.     

Growth of a Mixed Species Lactic Starter in a Continuous "pH-Stat" Fermentor

Optimum growth conditions for mixed species starter FDs 0172 in skim milk, whey medium, and tryptone medium at 25 C in a “pH-stat” continuous fermentor were investigated. Specific growth rate and productivity were found to be influenced both by the medium and the pH value. Highest productivity was found in skim milk medium between pH 5.5 and 5.9. Lactic acid-producing activity of harvested cells decreased by continuous cultivation at pH values lower than 5.9 to 6.1, especially in tryptone and whey medium. Bacterial balance, CO₂ production, and aroma formation were comparable to the control in skim milk and whey medium at any pH, but differed significantly for cells grown in tryptone medium.     

Preliminary investigation of a polyethylene glycol hydrogel "nerve glue"

Background

Polyethylene glycol (PEG) hydrogel is a biocompatible semi-adherent gel like substance that can potentially augment nerve repair much like a fibrin sealant. Potential advantages of this substance include fast preparation and set up time, as well as adhesion inhibiting properties. The purpose of this study was to perform an initial evaluation of PEG hydrogel in this application.

Methods

The sciatic nerves of 29 rats were transected and repaired using two 10-0 nylon sutures and either PEG hydrogel or fibrin glue. After 10 weeks, contraction forces of the reinnervated muscles were evaluated and histological assessment of scar tissue performed.

Results

Muscle strength testing revealed the average ratio of experimental to control sides for the fibrin glue group was 0.75 and for the PEG hydrogel group was 0.72 (no significant difference). Longitudinal sections through the nerve repair site showed no significant difference in nerve diameter but did demonstrate a significant reduction in scar thickness in the PEG hydrogel group (p < 0.01).

Conclusion

Though further study is necessary to fully evaluate, PEG hydrogel results in less scar tissue formation and equivalent muscle recovery as fibrin sealant when applied as a nerve glue in a rodent sciatic nerve repair model.     

Manitoba crash a wake-up call for "fly-in" physicians

A December plane crash in northern Manitoba served to remind the province''s "fly-in" physicians of the perils their work may entail. Four people were killed and 13 injured in the crash, which left Dr. Gerry Huot in serious condition in a Winnipeg hospital. The accident caused a serious head injury, and 4 months later he remains in hospital. It is causing some physicians to rethink their travel plans.     

Predictive power of "a minima" models in biology

Many apparently complex mechanisms in biology, especially in embryology and molecular biology, can be explained easily by reasoning at the level of the "efficient cause" of the observed phenomenology: the mechanism can then be explained by a simple geometrical argument or a variational principle, leading to the solution of an optimization problem, for example, via the co-existence of a minimization and a maximization problem (a min-max principle). Passing from a microscopic (or cellular) level (optimal min-max solution of the simple mechanistic system) to the macroscopic level often involves an averaging effect (linked to the repetition of a large number of such microscopic systems with possible random choice of the parameters of each of them) that gives birth to a global functional feature (e.g. at the tissue level). We will illustrate these general principles by building in four different domains of application "a minima" models and showing the main properties of their solutions: (1) extraction of a minimal RNA structure functioning as the first "peptidic machine," a kind of ancestral ribosome; (2) study of a genetic regulatory network of Drosophila centred on Engrailed gene and expressing successively two genes inside a limit cycle; (3) study of a genetic network regulating neural activity and proliferation in mammals; and (4) study of a simple geometric model of epiboly in zebrafish.     

Letter: Notes on "heat loss from a Newtonian animal"

Parker, Baker &; Smith (1972) have demonstrated mathematically that given the evolution of sexual reproduction, disruptive selection for the production of either many small gametes or a few large gametes may occur, resulting in a stable polymorphism of “sperm” and “egg” producers. Their model for the evolution of anisogamy requires only that zygote fitness (F) increase steeply with increases in zygote volume (V) (for Foc∝ V^x, x must be greater than 1·5) and that a sufficiently broad range of zygote productivity-size variants exist in the population (the higher the value of x, the broader the range needed). They suggest that anisogamy is almost universal in multicellular organisms but relatively rare in unicellular organisms because only for the former is an investment in extra gametic reserves at the expense of the number of gametes produced likely to be worthwhile in terms of increasing the survival probability of the zygote. In this note a graphical analysis and evidence from the anisogamous Protista will be presented concerning this hypothesis.     

Towards a functional understanding of "good genes"

The Hamilton & Zuk hypothesis (1982) underpins our understanding of the relationship between secondary sexual characters, parasites, and immunological function. However, despite the wealth of empirical studies that attempt to address issues raised by the Hamilton & Zuk hypothesis, there have been no overt attempts to identify the "good genes" that females select or how those good genes influence the host's immune system. Behavioural ecologists have generally viewed this aspect of immunity as a black box. In this review we propose candidate good genes in vertebrates, discuss their role in immune function and parasite resistance, and discuss several aspects of the assumptions that pervade studies of parasite mediated sexual selection in vertebrates. We also examine invertebrates (specifically insects) where our current knowledge of these systems suggests the patterns apparent in vertebrates are not underpinned by the same genetic mechanisms.     

Carotid artery stenting: a single center "real world" experience

Background

Percutaneous carotid artery stenting (CAS) became a widely used procedure in patients with symptomatic and asymptomatic carotid artery stenosis. However its role compared to carotid endarterectomy (CAD) remains questioned. We analysed the safety of carotid artery stenting program of a prospective CAS register program of a tertiary teaching hospital.

Method

Between July 2003 and December 2010, 208 patients underwent CAS procedure. Baseline, procedural and follow-up data were prospectively collected. Primary peri-interventional outcome was defined as 30-day major adverse events (MAE), including death, stroke or myocardial infarction, and mid- to long-term follow-up outcome included ipsilateral stroke, myocardial infarction or death. Secondary outcome was restenosis rate ≥50% per lesion.

Results

Unilateral carotid artery interventions were performed in 186 patients. In 22 patients CAS was performed bilaterally as stages procedures. The 30-day MAE rate was 1.9% consisting of two contralateral strokes and two ipsilateral stroke. Mean clinically follow-up was 22 months. Mid- to long-term MAE was 8.1% with 6.3% (n = 13) deaths, 1.9% (n = 4) myocardial infarctions and 0.9% (n = 2) ipsilateral stroke. The restenosis rate ≥50% per lesion was 4.3% at a mean follow-up of 22 months. Target lesion revascularization was performed in one patient, because of restenosis at 9 months follow-up after first CAS.

Conclusion

Implementation of a carotid artery stenting program at a tertiary, teaching hospital is a safe method for treatment of carotid artery stenosis. The adverse event rate during mid-to-long-term follow-up suggests an appropriate patient selection.     

Mitochondrial regular arrangement in muscle cells: a "crystal-like" pattern

The aim of this work was to characterize quantitatively the arrangement of mitochondria in heart and skeletal muscles. We studied confocal images of mitochondria in nonfixed cardiomyocytes and fibers from soleus and white gastrocnemius muscles of adult rats. The arrangement of intermyofibrillar mitochondria was analyzed by estimating the densities of distribution of mitochondrial centers relative to each other (probability density function). In cardiomyocytes (1,820 mitochondrial centers marked), neighboring mitochondria are aligned along a rectangle, with distance between the centers equal to 1.97 ± 0.43 and 1.43 ± 0.43 µm in the longitudinal and transverse directions, respectively. In soleus (1,659 mitochondrial centers marked) and white gastrocnemius (621 pairs of mitochondria marked), mitochondria are mainly organized in pairs at the I-band level. Because of this organization, there are two distances characterizing mitochondrial distribution in the longitudinal direction in these muscles. The distance between mitochondrial centers in the longitudinal direction within the same I band is 0.91 ± 0.11 and 0.61 ± 0.07 µm in soleus and white gastrocnemius, respectively. The distance between mitochondrial centers in different I bands is 3.7 and 3.3 µm in soleus and gastrocnemius, respectively. In the transverse direction, the mitochondria are packed considerably closer to each other in soleus than in white gastrocnemius, with the distance equal to 0.75 ± 0.22 µm in soleus and 1.09 ± 0.41 µm in gastrocnemius. Our results show that intermyofibrillar mitochondria are arranged in a highly ordered crystal-like pattern in a muscle-specific manner with relatively small deviation in the distances between neighboring mitochondria. This is consistent with the concept of the unitary nature of the organization of the muscle energy metabolism. confocal microscopy; quantitative analysis; cardiac and skeletal muscles; probability density function; unitary structure of cells     

"Homeward bound": a minimal care rehabilitation unit.

A 20 bed minimal care rehabilitation unit was set up by Newham District Health Authority in a small hospital originally scheduled for closure when a new district general hospital was opened. During the first year 114 patients were admitted (throughput 5.7), with a median length of stay of 30 days; in the second year 173 patients were admitted (throughput 8.65) with a median length of stay of 28.5 days. The cost per inpatient day was less than that of an inpatient day at the district''s long stay geriatric unit. Before the unit opened 24% of the acute beds had been occupied for more than six weeks, whereas two years later only 6% of the acute beds were occupied for such a period.     

Motile plant cell body: a "bug" within a "cage"

Analysis of the cytoskeleton in morphogenetically active plant cells allows us to propose a unified concept for the structural organization of eukaryotic cells. Their cytoarchitecture is determined by two principal structural complexes: nucleus-microtubule-based cell bodies ("bugs") and plasma-membrane-F-actin-based cell periphery complexes ("cages"). There are dynamic interactions between each of these entities in response to extracellular and intracellular signals. In the case of the cell body, these signals determine its polarization, rotation and migration. Interactions between cell body and cell periphery complexes determine cell growth polarity and morphogenesis throughout the eukaryotic kingdom.     

Axoneme specialization embedded in a "generalist" beta-tubulin

The relationship between the primary structure of the beta-tubulin C-terminal tail (CTT) and axoneme structure and function is explored using the spermatogenesis-specific beta2-tubulin of Drosophila. We previously showed that all beta-tubulins used for motile 9 + 2 axonemes contain a conserved sequence motif in the proximal part of the CTT, the beta-tubulin axoneme motif. The differential ability of tubulin isoforms and abilities of beta2-tubulin C-terminal truncations to form axonemes led us to hypothesize that the axoneme motif is essential for axoneme formation and the distal half of the CTT was less important. The studies we report here indicate that it is not that simple. Unexpectedly, some changes in the core sequence of the axoneme motif did not disrupt formation of motile axonemes. And, while deletion of the distal CTT did not disrupt the ability to produce functional sperm [Popodi et al., Cell Motil Cytoskeleton 2005;62:48-64], changing the amino acid sequence in this region can. Thus both regions are important. The deep conservation of the axoneme motif in all eukaryotic groups implies that the presence of the sequence motif confers a functional advantage. The central pair is the axoneme structure most sensitive to perturbations in tubulin molecules; we hypothesize central pair assembly is facilitated by the presence of this motif. Our data reveal that beta2-tubulin has robust properties for axoneme assembly, and that axonemal specializations are embedded in both the CTT and the body of the beta2 molecule.     

Campylobacter enteritis: a "new" disease.

By selective culture campylobacters (C jejuni and C coli) were isolated from the faeces of 57 (7-1%) out of 803 unselected patients with diarrhoea; none were isolated from 194 people who had not got diarrhoea. Specific agglutinins were found in the sera of 31 out of 38 patients with campylobacter enteritis and 10 of them had a rising titre. Half the patients were aged 15 to 44 years, but the incidence was highest in young children. All the patients with campylobacters had a distinctive clinical illness with severe abdominal pain. Campylobacters are a relatively unrecognised cause of acute enteritis, but these findings suggest that they may be a common cause. Spread of infection was observed within 12 out of 29 households, and in these cases children were usually implicated. Several patients were apparently infected from chickens, both live and dressed, and poultry may be the primary source of the organism. In two cases dogs with diarrhoea were found to be infected with strains indistinguishable from their human contacts. Ten patients acquired their infections while travelling abroad.     

Utilization of the "complex method" to optimize a fermentation process

The complex method has been applied to maximize the profit of a fermentation process. The optimization method is based on sequential search technique and may be implemented in most process which can be stimulated. Utilizing the derived optimal value of the controllable variables (the concentration of glucose, soybean meal, phosphate, and salt; agitation and aeration rates; inoculum size; and fermentation duration) resulted in a substantial profit increase.     

On the presence of a "particle-bound" neuraminidase in retina: a developmental study.

Neuraminidase activity was detected in chicken retina. A “particle-bound” neuraminidase was demonstrated in retina; however no “soluble” neuraminidase was present. For the endogenous “particle-bound” neuraminidase the pH optimum was 4.0 and the enzyme was stimulated by 0.15 % Triton X-100. Total activity measured in the presence of both endogenous and G_Dla (0.085 mM) substrates, reached a maximum at the same pH (4.0) in the presence of lower amounts of Triton X-100 (0.075–0.1 %). An excess of G_Dla inhibited the activity. Total and endogenous activity profiles of the “particle-bound” neuraminidase behaved similarly during chick retina ontogenesis; the activities were low during the early embryo period, reached maximum levels near hatching and remained stable throughout adulthood. In chicken retina, neuraminidase, which may take part in ganglioside catabolism, reached the maximum of activity when the retina was morphologically mature, while glycosyltransferases, implicated in the first steps of retinal ganglioside synthesis, are known to attain maximum levels of activity at an early stage of brain development.     

An energetic evaluation of a "Smith" collagen microfibril model.

An energy minimized three-dimensional structure of a collagen microfibril template was constructed based on the five-stranded model of Smith (1968), using molecular modeling methods and Kollman force fields (Weiner and Kollman, 1981). For this model, individual molecules were constructed with three identical polypeptide chains ((Gly-Pro-Pro) _n , (Gly-Prop-Hyp) _n , or (Gly-Ala-Ala) _n , wheren=4, 12, and 16) coiled into a right-handed triple-helical structure. The axial distance between adjacent amino acid residues is about 0.29 nm per polypeptide chain, and the pitch of each chain is approximately 3.3 residues. The microfibril model consists of five parallel triple helices packed so that a left-handed superhelical twist exists. The structural characteristics of the computed microfibril are consistent with those obtained for collagen by X-ray diffraction and electron microscopy. The energy minimized Smith microfibril model for (Gly-Pro-Pro)₁₂ has an axial length of about 10.2 nm (for a 36 amino acid residue chain), which gives an estimated D-spacing (234 amino acids per chain) of approximately 66.2 nm. Studies of the microfibril models (Gly-Pro-Pro)₁₂, (Gly-Pro-Hyp)₁₂, and (Gly-Ala-Ala)₁₂ show that nonbonded van der Waals interactions are important for microfibril formation, while electrostatic interactions contribute to the stability of the microfibril structure and determine the specificity by which collagen molecules pack within the microfibril.     

An atypical crista resembling a "tight junction" in bean root mitochondria

The conformation and structure of an atypical crista found in a small percentage of the mitochondria in root tip cells of Phaseolus vulgaris L. have been studied electron microscopically in material fixed in glutaraldehyde followed by osmium tetroxide. In its transformation into an atypical crista, a normal crista elongates, broadens, and flattens, and the inner leaflets of its apposed unit membranes appear to fuse in a manner analogous to the formation of "tight junctions" between certain animal cells. The result is a large platelike, quintuple-layered structure, 240–260 A thick, whose long axis parallels that of the mitochondrion. The outer layers of the "plate," bordering on the mitochondrial matrix, are thickened and exhibit striking patterns in the micrographs. The structure of the plate is compared with that previously described for tight junctions between animal cells.