Free-energy-based framework for early forecasting of stem cell differentiation

Commitment of stem cells to different lineages is inherently stochastic but regulated by a range of environmental bio/chemo/mechanical cues. Here, we develop an integrated stochastic modelling framework for predicting the differentiation of hMSCs in response to a range of environmental cues, including sizes of adhesive islands, stiffness of substrates and treatment with ROCK inhibitors in both growth and mixed media. The statistical framework analyses the fluctuations of cell morphologies over approximately a 24 h period after seeding the cells in the specific environment and uses the cytoskeletal free-energy distribution to forecast the lineage the hMSCs will commit to. The cytoskeletal free energy which succinctly parametrizes the biochemical state of the cell is shown to capture hMSC commitment over a range of environments while simple morphological factors such as cell shape, tractions on their own are unable to correlate with lineages hMSCs adopt.

Simulation of the cytoskeletal response of cells on grooved or patterned substrates

We analyse the response of osteoblasts on grooved substrates via a model that accounts for the cooperative feedback between intracellular signalling, focal adhesion development and stress fibre contractility. The grooved substrate is modelled as a pattern of alternating strips on which the cell can adhere and strips on which adhesion is inhibited. The coupled modelling scheme is shown to capture some key experimental observations including (i) the observation that osteoblasts orient themselves randomly on substrates with groove pitches less than about 150 nm but they align themselves with the direction of the grooves on substrates with larger pitches and (ii) actin fibres bridge over the grooves on substrates with groove pitches less than about 150 nm but form a network of fibres aligned with the ridges, with nearly no fibres across the grooves, for substrates with groove pitches greater than about 300 nm. Using the model, we demonstrate that the degree of bridging of the stress fibres across the grooves, and consequently the cell orientation, is governed by the diffusion of signalling proteins activated at the focal adhesion sites on the ridges. For large groove pitches, the signalling proteins are dephosphorylated before they can reach the regions of the cell above the grooves and hence stress fibres cannot form in those parts of the cell. On the other hand, the stress fibre activation signal diffuses to a reasonably spatially homogeneous level on substrates with small groove pitches and hence stable stress fibres develop across the grooves in these cases. The model thus rationalizes the responsiveness of osteoblasts to the topography of substrates based on the complex feedback involving focal adhesion formation on the ridges, the triggering of signalling pathways by these adhesions and the activation of stress fibre networks by these signals.

[Liver trauma due to penetrating lesions: miscellanea, personal case series, clinical and CT findings]

PURPOSE

Penetrating liver wounds are related to many causes and rank second after blunt abdominal and liver trauma. We will report the clinical and radiological findings of our personal series of patients with penetrating trauma, especially by firearms and stab and cut wounds. We will also try to define the diagnostic workup of these traumas, which is especially based on CT signs of liver damage and associated changes and which is of basic importance for following treatment, both surgical or conservative.

MATERIAL AND METHODS

In the last seven years we retrospectively reviewed 31 cases of penetrating liver trauma. The patients were 19 men and 12 women, ranging in age 18 to 73 (mean 42), with penetrating liver injuries from firearms (16 patients) and stab (9 cases) wounds; 6 patients had injuries from different causes. Abdominal CT was carried out in emergency with the CT Angiography (CTA) technique in all patients. In the patients with suspected chest and abdomen involvement CT was performed from the mid-chest for accurate assessment of diaphragm and lung bases and to exclude associated pleuropulmonary damage.

RESULTS

Penetrating liver wounds were caused by firearms in 70% of cases, by stabbing in 12% and, in the extant 18%, by other causes such as home accidents, road and work traumas, and liver biopsy. In our series, the liver was most frequently involved, especially by firearms wounds; in our 16 cases the most frequent injuries were hemorrhagic tears. We found bullets in the liver in 6 cases. In one case of home accident the patient wounded himself while slicing bread with a long knife, which cut into the anterior abdominal wall and tore the anterior liver capsule, as seen at CTA.

DISCUSSION AND CONCLUSIONS

Penetrating wounds to liver and abdomen are less frequent than those to the chest. In the past decade the use of CT has changed the diagnostic and therapeutic approach to such injuries completely, decreasing the resort to explorative laparotomy and hepatorrhaphy. Indeed, CT provides a clear picture of the extent and severity of damage, which permits to choose a conservative treatment in case of intraparenchymal hematomas and lacerocontusive foci without hemoperitoneum, which can be followed-up with physical and CT examinations. Moreover, Helical CT could provide the early diagnosis of active bleeding in the peritoneum and of focal bleeding in the liver, thus permitting prompt hepatorrhaphy or targeted hepatectomy. A diaphragm injury suspected at CT should always prompt the surgeon to intervention, especially when hemothorax, lung base pneumothorax, large liver hematoma or tear of the liver dome are associated. Finally, subdiaphragmatic free gas indicates gut perforation associated with liver damage, in which case surgery is necessary too.

Primary malignant lymphoma of the mandible

From 1945 through 1985, 32 cases of primary lymphoma of bone were treated at the University of Iowa Hospitals and Clinics. Sixteen cases (50%) demonstrated the lesion in the long tubular bones with a predilection for the lower and upper extremities. The frequently involved flat bones (six cases) were the bones of the pelvis. There were only three cases (9%) where the mandible was the primary site. In this report, the literature is reviewed and three cases with primary lymphoma of the mandible are presented.

Postoperative adjuvant radiotherapy for adenocarcinoma of the rectum and rectosigmoid

One hundred five patients treated with potentially curative surgery and adjuvant postoperative radiotherapy for adenocarcinoma of the rectum and rectosigmoid from 1973 through 1981 were reviewed. Radiation therapy was given with 18-25 MeV X rays in doses of 40-50 Gy in 5 weeks (midline dose) using AP-PA fields in 97 patients. A boost of 6 to 10 Gy was directed to the area of maximum risk by anterior-posterior or perineal fields in 71 patients. Local failure occurred in 15 patients and was documented pathologically in 8 patients, or clinically or radiologically in 7 patients. The local recurrences according to the Modified Astler-Coller staging criteria were: B1: 0% (0/3); B2: 4% (1/24); B3: 31% (4/13); C1: 8% (1/12); C2: 18% (8/45); C3: 20% (1/5). Local failure after adjuvant radiotherapy versus surgery alone was compared. The comparison of local failure of combined treatment versus surgery alone, from our institution, is as follows: B2-4% vs 13%, B3-31% vs 26%, C2-18% vs 30%, and C3-20% vs 49%. Sixty-one patients (58.1%) have been followed for 5 years, with a median of 73 months and a minimum of 24 months. The actuarial 5-year survival (disease-free) for the entire group is 55% and is not statistically different for the groups with negative or positive nodes. Fourteen patients (13%) required surgery for small bowel complications; four others (4%) had symptomatic small bowel obstruction treated with conservative therapy only. Small bowel obstruction occurred in 4 of 16 (25%) treated with radiation fields above L5, whereas those treated below L5 had an 11% incidence. Postoperative adjuvant radiotherapy can increase local tumor control compared to surgery alone. The small bowel complication rate in this series most likely reflects AP-PA treatment technique and can be decreased by the use of multiple fields with maximum shielding of the small intestine.

Thyroid lymphomas stages IE and IIE: comparative results for radiotherapy only, combination chemotherapy only, and multimodality treatment

This study was undertaken to ascertain the influence of both more precise staging and more intensive treatment on results in 38 patients with Stage IE and IIE lymphomas of the thyroid. These patients were admitted between 1947 and 1984. Using the modified Rappaport system, the disease was classified as diffuse large cell in 32 patients. The initial investigation included lymphangiography in 25 patients, five of which had a staging laparotomy. The assigned stages were IEA--11, IEB--1, and IIEA--26. Treatment consisted of definitive radiotherapy alone in 15; combination chemotherapy and radiotherapy in 14; and chemotherapy alone in 6 patients. The remaining three patients were treated with surgery alone. In general, combination chemotherapy consisted of cyclophosphamide, Adriamycin, vincristine, and prednisone, with or without bleomycin (CHOP +/- Bleo). The overall 5-year survival and disease-free survival were 72 and 64%, respectively. For patients treated with radiotherapy only, results depended on stage. For Stage IE, the survival and disease-free survival were 100 and 83%, respectively. The corresponding Stage IIE results were 88 and 75%. Within this group, results were better for a subset of patients where disease did not involve the mediastinum. Survival and disease-free survival for combined modality treatment were both 77% (10 of these 17 patients had Stage IIE disease). Survival and disease-free survival for combination chemotherapy were 53 and 30% (all had Stage IIE disease). In conclusion, radiotherapy alone is excellent treatment for disease limited to the thyroid with or without cervical adenopathy. Results for patients with mediastinal extensions was unsatisfactory and the addition of combination chemotherapy is indicated.