The impact of class I compression stockings on the peripheral microperfusion of the lower limb: A prospective pilot study

OBJECTIVE

The use of medical compression stockings (MCS) in patients with peripheral arterial disease (PAD) and diabetes is the subject of an ongoing critical debate. While reducing leg edema of various origins by improving venous back flow, there is a concern about additional arterial flow obstruction when compression therapy is applied in pre-existing PAD. The aim of this study is to obtain further information on the use of class I MCS in patients with advanced PAD and to evaluate the framework conditions for a safe application.

METHODS

The total collective (n = 55) of this prospective, clinical cohort study consisted of 24 patients with PAD Fontaine stage IIb and higher studied before revascularization, of whom 16 patients were examined again after revascularization, and 15 healthy participants included for reference. The microperfusion of the lower extremity of all participants was examined in a supine, elevated, and sitting position using the oxygen to see (O2C) method.

RESULTS

The results indicate that leg positioning had the strongest influence on microcirculation (SO2 and flow: p = 0.0001), whereas MCS had no significant effect on the perfusion parameters (SO2: p = 0.9936; flow: p = 0.4967) and did not lead to a deterioration of values into critical ranges.

CONCLUSION

Mild medical compression therapy appears to be feasible even in patients with advanced PAD. Larger studies are warranted to observe any long-term effects, in particular for the treatment of reperfusion edema after revascularization.

First experiences of ultrasound vector flow imaging at the femoropopliteal artery in peripheral arterial disease

Background: The femoropopliteal artery (FPA) plays a central role in diagnosing and treating peripheral arterial disease (PAD). FPA lesions are the most frequent cause of intermittent claudication, and no other artery of the lower extremities is recanalised more frequently. Generally, ultrasound is the primary imaging tool in PAD, particularly FPA. With the development of high-frame-rate ultrasound technology in addition to traditional ultrasound modes, vector flow imaging (VFI) has provided deeper haemodynamic insights when used in the carotid artery. Here, we report the use of VFI at the FPA level in routine PAD examinations. Patients and methods: In this single-centre prospective study, we evaluated consecutive patients with PAD using B-mode imaging, colour Doppler, pulsed wave Doppler (PW) and vector flow. Hemodynamic parameters at predefined locations at the carotid artery and FPA were compared. Results: Qualitatively adequate VFI at all sites was possible in 76% of the patients with PAD. With decreasing volume flow from the common carotid artery to the internal carotid artery and from the common femoral artery via the superficial femoral artery to the popliteal artery, the correlation between VFI- and PW-derived-volume flow was high at every site. Based on different techniques, the VFI-derived values were significantly lower than the PW-derived values. The mean wall shear stress was significantly lower at all femoropopliteal sites than at the carotid sites, whereas the oscillatory shear index at the femoral site was higher than that at the carotid sites rather than at the popliteal location. Conclusions: Our findings suggest that vector flow data acquisition in the FPA is feasible in most patients with PAD. Therefore, with knowledge of the method and its limitations, VFI provides haemodynamic information beyond traditional ultrasound techniques and is a promising new tool for flow analysis in PAD.

Prognostic value of extended cardiac risk assessment before elective open abdominal aortic surgery

BACKGROUND

Major vascular surgery is associated with a high perioperative risk and significant mortality. Despite advances in risk stratification, monitoring, and management of perioperative complications, cardiac complications are still common. Stress echocardiography is well established in coronary artery disease diagnostics; however, its prognostic value before high-risk aortic surgery is unknown. This prospective, single-center study compared the outcome of patients undergoing extended cardiac risk assessment before open abdominal aortic surgery with the outcome of patients who had received standard preoperative assessment.

METHODS

The study included patients undergoing elective open abdominal aortic surgery. Patients who underwent standard preoperative assessment before the start of a dedicated protocol were compared with patients who had extended cardiac risk assessment, including dobutamine stress echocardiography, as part of a stepwise interdisciplinary cardiovascular team approach. The combined primary endpoint was cardiovascular death, myocardial infarction, emergency coronary revascularization, and life-threatening arrhythmia within 30 days. The secondary endpoint was acute renal failure and severe bleeding.

RESULTS

In total, 77 patients (mean age 68.1 ± 8.1 years, 70% male) were included: 39 underwent standard and 38 underwent cardiac risk assessment. The combined primary endpoint was reached significantly more often in patients before than after implementation of the extended cardiac stratification procedure (15% vs. 0%, p = 0.025). The combined secondary endpoint did not differ between the groups.

CONCLUSIONS

Patients with extended cardiac risk assessment undergoing elective open abdominal aortic surgery had better 30-day outcomes than did those who had standard preoperative assessment.

Investigation of Different Methods of Intraoperative Graft Perfusion Assessment during Kidney Transplantation for the Prediction of Delayed Graft Function: A Prospective Pilot Trial

Delayed graft function (DGF) after renal transplantation is a relevant clinical problem affecting long-term organ function. The early detection of patients at risk is crucial for postoperative monitoring and treatment algorithms. In this prospective cohort study, allograft perfusion was evaluated intraoperatively in 26 kidney recipients by visual and formal perfusion assessment, duplex sonography, and quantitative microperfusion assessment using O2C spectrometry and ICG fluorescence angiography. The O2C tissue spectrometry device provides a quantitative method of microperfusion assessment that can be employed during kidney transplantation as an easy-to-use and highly sensitive alternative to ICG fluorescence angiography. Intraoperative microvascular flow and velocity in the allograft cortex after reperfusion predicted DGF with a sensitivity of 100% and a specificity of 82%. Threshold values of 57 A.U. for microvascular flow and 13 A.U. for microvascular velocity were identified by an ROC analysis. This study, therefore, confirmed that impairment of microperfusion of the allograft cortex directly after reperfusion was a key indicator for the occurrence of DGF after kidney transplantation. Our results support the combined use of intraoperative duplex sonography, for macrovascular quality control, and quantitative microperfusion assessment, such as O2C spectrometry, for individual risk stratification to guide subsequent postoperative management.

Polyvascular disease, pulse pressure and mortality

Background: Peripheral arterial disease (PAD), coronary artery disease (CAD) and carotid stenosis (CS) are robust predictors of mortality. The value of individual vascular beds in polyvascular disease (PVD) to predict mortality in patients with atherosclerotic burden is not clear. Therefore, we have examined the predictive value of PAD, CAD and CS in patients at intermediate to high risk of cardiovascular (CV) disease. Patients and methods: In our retrospective observational study we analyzed baseline data from the Ludwigshafen Risk and Cardiovascular Health (LURIC) study, a monocentric cohort study of 3316 patients referred to coronary angiography. Results: As the number of atherosclerotic vascular beds increased, the hazard ratios (HRs) for both all-cause mortality and CV mortality significantly increased in a multivariate analysis after adjusting for age, sex, body mass index, diabetes mellitus and estimated glomerular filtration rate, with HRs of 1.36 (95%CI: 1.11-1.68), 2.56 (95%CI: 2.01-3.26), 2.84 (95%CI: 1.93-4.17) and 1.56 (95%CI: 1.19-2.06), 2.70 (95%CI: 1.97-3.72), 3.50 (95%CI: 2.19-5.62), respectively. The combination of PAD with either CAD or CS was associated with higher HRs for all-cause (HR 2.81 and 7.53, respectively) and CV (HRs 2.80 and 6.03, respectively) mortality compared with the combination of CAD and CS (HRs 1.94 and 2.43, respectively). The presence of PVD was associated with higher age, systolic blood pressure, pulse pressure (PP; a marker of vascular stiffness), former smoking and inversely with lower eGFR. Conclusions: We show that as the number of atherosclerotic vascular beds increases, all-cause and CV mortality rates increase in parallel. Simultaneous prevalence of PAD is associated with significantly higher all-cause and CV mortality rates compared with CS coexistence. Furthermore, increasing atherosclerotic load may contribute to vascular stiffness and impaired renal function.

Patient and Graft Survival After Dual Kidney Transplantation With Marginal Donors in Comparison to Matched Control Groups

BACKGROUND

Postmortal organ donor rates remain low in Germany, whereas donor age has been increasing considerably in the last decades. As a consequence of low donation rates older and more marginal donor kidneys are accepted for transplantation. However, procured kidneys from very old a/o marginal donors may be considered as not suitable for transplantation as a single organ and subsequently be discarded. However, dual transplantation of both kidneys from such donors may provide an opportunity to nevertheless use these organs for renal transplantation, thereby providing the twofold nephron mass as a single kidney transplantation.

METHODS

We compared in this retrospective analysis the outcome of 10 recipients of a dual kidney transplantation (DKT) with 40 matched recipients of a single kidney transplantation (SKT). Recipients were matched for donor and recipient age (ie, a maximum age difference of ±10 years in a ratio of 1:4 for DKT vs SKT recipients). In addition, a second SKT control group of 10 SKT recipients being transplanted immediately before each DKT recipient with a kidney from a donor aged ≥65 years was used for comparison. All renal transplant recipients were observed for up to 3 years or until July 31, 2020.

RESULTS

Mean donor and recipient age was 77.2 ± 4.6/75.1 ± 6.6/82.1 ± 7.9 and 66.4 ± 5.8/66.1 ± 6.0/64.8 ± 8.4 for SKT group 1/SKT group 2/DKT, respectively. Procurement serum creatinine concentrations were significantly higher in the DKT group in comparison to the SKT control group 1 (P = .019) as was the rate of transplant artery atherosclerosis (P = .021). Furthermore, Kidney Donor Profile Index, and Kidney Donor Risk Index were significantly higher (P = .0138/P = .064, and P < .001/P = .038) in the DKT group than in SKT group 1 and 2. Rates of acute rejection and delayed graft function were not significantly different between groups, though biopsy-proven acute rejection was numerically higher in the SKT groups. Patient survival and overall and death-censored graft survival rates were also not significantly different between groups, although they tended to be higher after DKT.

CONCLUSIONS

DKT provides an opportunity to successfully use postmortal kidneys even from donors aged >80 years and a Kidney Donor Profile Index ≥95% for renal transplantation. DKT may thereby increase the available pool of donors to better serve patients with end-stage renal disease on the waiting list.

A Modified Surgical Model of Hind Limb Ischemia in ApoE-/- Mice using a Miniature Incision

The purpose of this study is to introduce and evaluate a modified surgical approach to induce acute ischemia in mice that can be implemented in most animal laboratories. Contrary to the conventional approach for double ligation of the femoral artery (DLFA), a smaller incision on the right inguinal region was made to expose the proximal femoral artery (FA) to perform DLFA. Then, using a 7-0 suture, the incision was dragged to the knee region to expose the distal FA. Magnetic resonance imaging (MRI) on bilateral hind limbs was used to detect FA occlusion after the surgery. At 0, 1, 3, 5, and 7 days after the surgery, functional recovery of the hind limbs was visually assessed and graded using the Tarlov scale. Histologic evaluation was performed after euthanizing the animals 7 days after DLFA. The procedures were successfully performed on the right leg in ten ApoE^-/- mice, and no mice died during subsequent observation. The incision sizes in all 10 mice were less than 5 mm (4.2 ± 0.63 mm). MRI results showed that FA blood flow in the ischemic side was clearly blocked. The Tarlov scale results demonstrated that hind limb function significantly decreased after the procedure and slowly recovered over the following 7 days. Histologic evaluation showed a significant inflammatory response on the ischemic side and reduced microvascular density in the ischemic hind limb. In conclusion, this study introduces a modified technique using a miniature incision to perform hind limb ischemia (HLI) using DLFA.

[Influence of tapentadol retard on functional parameters in patients with severe chronic pain--is there a benefit in daily life?]

BACKGROUND

A patient-orientated therapy management for patients with severe chronic pain includes effective analgesia, improvement of health related quality of life and improvement of functionality.

PATIENTS AND METHOD

In this prospective, non-interventional trial in 630 patients with severe chronic pain mostly due to chronic low back pain or gonarthrosis, treatment with tapentadol retard was evaluated with respect to its effects on analgesia, functionality and quality of life. Collected data included pain intensity, painDETECT,SF-12, FFbH-R and FFbH-OA.

RESULTS

Mean pain intensity decreased significantly (NRS-3: -3.2 points, p < or = 0.001) and in 47.9% of the patients the mean pain intensity was reduced by at least 50%. Health-related quality of life and functionality improved significantly. Tolerability was good. The known tolerability profile of tapentadol retard could be confirmed.

CONCLUSION

In this study in real-life-setting tapentadol was effective in terms of analgesic effect but also in terms of improvementof health-related quality of life and functionality, leading to a benefit for the patient in daily life.

Tapentadol prolonged release for severe chronic pain: results of a noninterventional study involving general practitioners and internists

This noninterventional, prospective study investigated the administration of tapentadol prolonged release (PR; the dosage form described in this article is commercially available in Germany as Palexia retard; Grünenthal GmbH, Aachen) for severe chronic pain in routine clinical practice over a 3-month period. Effectiveness analyses included data from 3134 patients; 1331 received World Health Organization (WHO) Step III pretreatment. A total of 97.8% of patients received long-term analgesic pretreatment (42.5% with strong opioids). Switching to tapentadol PR produced a 3.9-point mean pain reduction (baseline, 7.0 ± 1.5; end of observation, 3.1 ± 1.8; 11-point numerical rating scale; descriptive P value ≤.001); 72.1% of patients experienced clinically relevant pain relief (≥50%) at the end of observation. Significant decreases in pain-related impairment of daily activities and improvements in quality of life (descriptive P value ≤.001) were observed with tapentadol PR with good tolerability. Tapentadol PR was effective for various pain indications in patients previously receiving strong opioids (67.2% achieved clinically relevant pain relief). Tapentadol PR can be considered an alternative therapy to classical opioids for treatment of severe chronic pain.

[Pain therapy in the elderly:7-day transdermal buprenorphine patch in clinical practice. Results of a non-interventional study]

BACKGROUND

Chronic pain in the elderly is common. Especially in the elderly inadequate treatment of pain can cause significant functional impairmentand deterioration of qualityof life.

METHODS

Theaim of this post-marketing surveillance study was to collect data from clinical practice on the analgesic efficacy and safety of the 7-day transdermal buprenorphine patch in patients with chronic non-malignant pain pre-treated with opioids. A total of 2713 elderly multimorbid patients were switched to 7-day transdermal buprenorphine patch from previous opioid treatment mainly due to inadequate analgesia. 83% of patients received a 7-day transdermal buprenorphine patch dosage > or = 10 microg/h. During the 8-weekobservation period, data on pain intensity, quality of sleep/life (NRS-11 point scales) and safety wererecorded.

RESULTS

Mean pain intensity decreased by 4 points with 7-day transdermal buprenorphine patch (p < or = 0.001). Quality of sleep and life as well as social activities and self-reliance improved significantly. Compliance and tolerability were assessed as very good/good in > 90% of patients. Adverse drug reactions (ADRs) occurred in 3% of patients and corresponded to 90.1% to the already-known spectrum of ADRs of 7-daytransdermal buprenorphinepatch.

CONCLUSIONS

The results confirm that elderly patients with opioid pre-treatment benefit from a switch to 7-day transdermal buprenorphine patch with regard to reduction of pain and improved quality of life.

Effect of different liver resection methods on liver damage and regeneration factors VEGF and FGF-2 in mice

BACKGROUND

Different approaches to study liver regeneration in murine models have been proposed. We investigated the effect of different liver resection models on liver damage and regeneration parameters in mice.

METHODS

We compared the technical aspect of the 2 most commonly used techniques of 50% and 70% liver resection. Liver damage, as determined by the change in serum alanine aminotransferase and aspartate aminotransferase, as well as the regeneration parameters VEGF and FGF-2 were analyzed at 6 time points. A postoperative vitality score was introduced.

RESULTS

Cholestasis was not observed for either technique. Both resection techniques resulted in full weight recovery of the liver after 240 hours, with no significant difference between sham and resection groups. Postoperative animal morbidity and total protein levels did not differ significantly for either method, indicating early and full functional recovery. However, comparing the mitogenic growth factors FGF-2 and VEGF, a significant increase in serum levels and, therefore, increased growth stimulus, was shown in the extended resection group.

CONCLUSION

Extended resection led to a greater response in growth factor expression. This finding is important since it shows that growth factor response differs acdording to the extent of resection. We have demonstrated the need to standardize murine hepatic resection models to adequately compare the resulting liver damage.

[Tapentadol prolonged release for the treatment of severe chronic tumor pain in routine clinical practice]

STUDY OBJECTIVE

This subgroup analysis of a non-interventional study involving general practitioners and internists investigated the administration of tapentadol prolonged release (Palexia retard) for the treatment of severe chronic tumor pain in routine clinical practice in Germany.

METHODS

Data of all patients in the study cohort who were exclusively diagnosed with tumor pain (n = 143) were included in this analysis. Data collection during the 3-month observation period included previous and concomitant analgesic treatment, tapentadol PR dosage, pain intensity, sleep and quality of life parameters, and tolerability of tapentadol PR.

RESULTS

A total of 96.5% of all patients with tumor pain had already received analgesic long-term treatment prior to initiation of tapentadol PR therapy, 49.0% of those strong opioids. Switching to tapentadol PR resulted in a mean pain reduction of 3.8 points from 7.1 +/- 1.4 at baseline to 3.3 +/- 1.9 at end of observation (NRS-11, 11-point pain scale; descriptive pvalue < or = 0.001). At end of observation, 67.4% of the patients had experienced a clinically relevant pain relief of > or = 50%, and 89.9% of the patients attained either their intended pain reduction and/or an additional individual treatment goal; both goals had been predefined at start of tapentadol PR treatment. This was accompanied by a significant decrease in pain-related impairments of daily activities and an improvement in quality of life (descriptive p value < or = 0.001) with an overall good tolerability of tapentadol PR. Treatment with tapentadol PR was assessed positively by physicians and patients.

CONCLUSIONS

Treatment with tapentadol PR resulted in marked effective and well tolerated relief of severe tumor pain accompanied by an improvement of pain-related impairments of daily activities and quality of life in this routine clinical practice non-interventional study. Tapentadol PR--an innovative effective analgesic--might thus provide an alternative treatment option in the management of tumor pain.

[Tapentadol prolonged release for severe chronic pain. Results of a non-interventional study involving general practitioners and internists]

STUDY OBJECTIVE

This prospective, non-interventional study involving general practitioners and internists in Germany investigated the administration of tapentadol prolonged release (Palexia retard) for the treatment of severe chronic pain in routineclinical practice over a 3-month observation period.

METHODS

Collected data included tapentadol PR dosage, previous and concomitant analgesic treatment, pain intensity, sleep and quality of life parameters, and tolerability of tapentadol PR. Effectiveness was analyzed for 3134 patients; additionally, a subgroup analysis was performed in 1331 patients with WHO III pretreatment.

RESULTS

A total of 97.8% of all patients received analgesic long-term pretreatment, 42.5% of those strong opioids. Switching to tapentadol PR resulted in a mean pain reduction of 3.9 points from 7.0 +/- 1.5 at baseline to 3.1 +/- 1.8 at end of observation (NRS-11, 11-point pain scale; descriptive p value < or = 0.001); 72.1% of patients experienced a clinically relevant pain relief of > or = 50% at end of observation. A total of 89.4% of the patients attained either their intended pain reduction and/or an additional individual treatment goal at end of observation; both were established at start of tapentadol PR treatment. This was accompanied by a significant decrease in pain-related impairments of daily activities and an improvement in quality of life (descriptive p value < or = 0.001) with an overall good tolerability of tapentadol PR. In particular, good effectiveness of tapentadol PR treatment was reported for various pain indications in patients who had already previously been treated with strong opioids. A clinically relevant pain reduction > or = 50% was achieved in 67.2% of these patients.

CONCLUSIONS

Tapentadol PR can be considered an alternative therapy to classical opioids for the treatment of severe chronic pain. Particularly for severe chronic pain requiring long-term medication, a reduction of common opioid side-effects with tapentadol PR therapy could contribute to better patient compliance.

Fluorescence lifetime imaging microscopy of chemotherapy-induced apoptosis resistance in a syngenic mouse tumor model

During cancer therapy with DNA-damaging drug-agents, the development of secondary resistance to apoptosis can be observed. In the search for novel therapeutic approaches that can be used in these cases, we monitored chemotherapy-induced apoptosis resistance in a syngenic mouse tumor model. For this, syngenic murine colorectal carcinoma cells, which stably expressed a FRET-based caspase-3 activity sensor, were introduced into animals to induce peritoneal carcinomatosis or disseminated hepatic metastases. This syngenic system allowed in vitro, in vivo and ex vivo analysis of chemotherapy induced apoptosis induction by optically monitoring the caspase-3 sensor state in the tumor cells. Tumor tissue analysis of 5-FU treated mice showed the selection of 5-FU-induced apoptosis resistant tumor cells. These and chemo-naive fluorescent tumor cells could be re-isolated from treated and untreated mice and propagated in cell culture. Re-exposure to 5-FU and second line treatment modalities in this ex-vivo setting showed that 5-FU induced apoptosis resistance could be alleviated by imatinib mesylate (Gleevec). We thus show that syngenic mouse systems that stably express a FRET-based caspase-3 sensor can be employed to analyse the therapeutic efficiency of apoptosis inducing chemotherapy.

Doxorubicin and mitoxantrone drug eluting beads for the treatment of experimental peritoneal carcinomatosis in colorectal cancer

We investigated the therapeutic efficiency of sulfonate-modified polyvinyl alcohol beads loaded with doxorubicin, irinotecan or mitoxantrone in vitro and in vivo in a model of experimental peritoneal carcinomatosis (PC). In vitro, cell proliferation was efficiently impaired by doxorubicin drug eluting bead (DEB) treatment while mitoxantrone DEBs were less effective than. Irinotecan showed little effect for both DEBs and free drug. Apoptosis was not different between free mitoxantrone and the DEB form while more apoptosis induction was observed in cells incubated with free doxorubicin and irinotecan. Experimental PC was produced in mice. The therapeutic efficiency of either mitoxantrone and doxorubicin DEB or free drugs were compared. Mice were treated either once on day 12 or by 3 repetitive applications on days 7, 10 and 12. Mice treated by DEBs showed less weight loss and mortality. Therapeutic effect was determined by measuring tumor volume and tumor load on the day 15 after tumor inoculation. For the single application on the day 12, an advantage could be observed for the free drugs. After 3 repeated injections of both free and mitoxantrone DEB no difference in tumor load or tumor volume could be observed. Least tumor load and tumor volume was observed in mice that received 3 repeated injections of doxorubicin DEB. No animal survived 3 injections of free doxorubicin. We conclude that bead encapsulation of chemotherapeutic drugs may show the advantage of less toxicity in peritoneal spread of colorectal cancer.

Acute GI bleeding by multiple jejunal gastrointestinal autonomic nerve tumour associated with neurofibromatosis type I

We describe a surgical emergency due to GI-bleeding caused by gastrointestinal autonomic nerve tumours (GANT s) in a patient with von Recklinghausen s disease. A 72 year old female patient with von Recklinghausen s disease was admitted with maelena. Endoscopy showed no active bleeding in the stomach and the colon. Therefore an angio-CT-scan was performed which revealed masses of the proximal jejunum as source of bleeding. Laparotomy was indicated and a 20 cm segment of jejunum which carried multiple extraluminal tumours was resected. The source of the bleeding was a 2 cm tumour which had eroded the mucosal surface. Immunohistologically, evidence of neuronal differentiation could be shown in the spindle-formed cells with positive staining for C-Kit (CD 117), CD 34, and a locally positive staining for synaptophysine and S100. This case report illustrates the association between neurofibromatosis and stromal tumours and should alert surgeons and gastroenterologist about gastrointestinal manifestations in patients with von Recklinghausen s disease.

Radiation-enhanced differentiation of erythroid progenitor cells and its relation to reproductive cell death

Terminally differentiated cells usually do not divide and are, thus, reproductively dead. To elucidate the significance of radiation-enhanced differentiation to reproductive cell death, murine erythroid progenitor cells were gamma-irradiated in plasma clot cultures and the development of haemoglobinized clones was studied thereafter. If irradiation occurred when the cells had resumed proliferation, the total numbers of haemoglobinized clones and, in parallel, the numbers of newly haemoglobinized clones were elevated above control levels 6-24 h after 10-30 Gy and 24-48 h after 1 Gy respectively. Thereafter, clone numbers decreased below controls. This decrease was faster with the newly haemoglobinized clones, indicating that both the accumulation of haemoglobinized clones and fast exhaustion of the pool of more primitive precursors in the cultures are due to accelerated differentiation. The haemoglobinized clones appearing after irradiation were reduced in size without indication of direct cell death. We conclude that the reproductive cell death occurring in our system is due to enhancement of differentiation. Enhancement of differentiation is expressed by omission of cell cycles normally passed through by the cell progeny before terminal differentiation is reached. Dependence of differentiation enhancement on the presence of cycling cells at the time of irradiation indicates involvement of growth of essential cytoplasmic constituents during mitotic delay as observed in other cell systems.

Induction of differentiation in erythroleukemic K562 cells by gamma-irradiation

Various agents have been shown to induce differentiation in neoplastic cells. The present study aimed at investigating comparable phenomena induced by high doses of gamma-irradiation in the presence of physiological factors. The erythroleukemic K562 cells were gamma-irradiated or treated with cytosine-arabinoside (Ara-C), and examined for cell size, protein content, acetylcholinesterase (AChE)-activity and hemoglobin synthesis in relation to mitotic activity. At doses above 10 Gy, differentiation was induced, as recognized by elevated AChE-activity, accompanied by an increase in cell size and protein content and cessation of cell proliferation. Moreover, irradiation, as well as Ara-C, induced hemoglobin synthesis when cultures were supplemented with hemin prior to treatment. It is suggested that the basic mechanisms of differentiation induction are similar for ionizing radiation and certain chemical agents and are related to continued growth of essential cytoplasmic constituents during inhibition of mitotic activity.

Review: a major component of radiation action: interference with intracellular control of differentiation

If genetic lesions were the sole reason of damage induced by ionizing radiation, an increase in the number of identical chromosome sets (polyploidy) may be expected to have a radioprotective effect. This effect is evident in terminally differentiated tissues when the reduction in remaining life span is used as the criterion. This effect is also evident in cells capable of proliferation if cytoplasmic growth during the period of mitotic delay is restricted and the criterion used is continuation of cell proliferation. Both instances demonstrate that polyploidy, in principle, can exert a radioprotective effect, although the genetic damage induced by a given dose increases in approximate proportion to ploidy. However, in mitotically active cells, without restrictions in cytoplasmic growth, differentiation enhancement dominates the effects of genetic lesions, and polyploidy does not protect. Enhancement of differentiation causes damage by eliminating amplification divisions normally passed through by cell progenies before terminal differentiation, thus reducing the number of differentiated cells produced. From its dependence on excess cytoplasmic growth it is concluded that the phenomenon is caused by the interference of ionizing radiation with a mechanism that provides intracellular signals needed to coordinate molecular interactions involved in the control of cell differentiation. This conclusion corresponds to experiments that suggest that intracellular control of differentiation depends on an increase in the ratio of essential cytoplasmic constituents, probably mitochondrial genomes, per nuclear genome. The action of chemical differentiation enhancing agents is similar and an outline of probable mechanisms is presented. Regarding late radiation damage it is concluded that non-specific genetic lesions can enhance differentiation by permanently prolonging the cell cycle, which causes an increased cytoplasmic growth rate per cycle. In this case polyploidy cannot protect because the induced genetic lesions are proportional to ploidy. Both the duration of mitotic delay, and the extent of genetic lesions increase with chromosome size, thus explaining the correlation between interphase chromosome volume and radio-sensitivity. Lack of substantial radioprotecting effect of polyploidy in neoplastically transformed mammalian cells indicates residual capabilities to cease cell proliferation by mechanisms related to terminal differentiation, thus offering clues to tumour therapy.

Lipid peroxidation in microsomes of murine bone marrow after low-dose gamma-irradiation

The principal aim of the study was to investigate the effect of low-dose gamma-irradiation on lipid peroxidation (LPO) in murine bone marrow. To this end, the degree of LPO in suspensions of microsomes of murine bone marrow cells (BMC) was determined in terms of malondialdehyde (MDA) formation after whole-body or in vitro exposure to various doses of gamma-radiation. These effects were compared to some extent with similar effects in liver and spleen preparations. As to the effect of gamma-irradiation on LPO in BMC, the response depends on the dose level and on whether whole-body or in vitro exposures are involved. Whole-body irradiation did not result in an increase in LPO in BMC microsomes, even at such high doses as 15 Gy, although hepatic microsomes showed a marked increase. In contrast, in vitro irradiation of BMC microsomes with 0.1, 10 and 50 Gy brought about an increase in LPO. This increase was already significant (P < 0.05) at 0.1 Gy following a post-irradiation incubation and substantial at 50 Gy, even without subsequent incubation. The results show that low doses of gamma-irradiation are able to induce an elevation of LPO in murine BMC microsomes, but only after in vitro irradiation. In the case of whole-body irradiation cellular radical scavengers and other metabolic reactions may prevent a measurable increase in LPO. This is partly illustrated by the case of vitamin-E deficiency, where a substantial increase in LPO in BMC microsomes is observed even without gamma-irradiation in comparison with euvitaminotic mice because normally occurring radicals are not scavenged sufficiently.

Terminal differentiation of human fibroblasts is induced by radiation

In order to analyze the effect of various kinds of radiation on the terminal differentiation processes of fibroblasts in culture, both human skin and lung fibroblasts were irradiated with electromagnetic non ionizing as well as ionizing radiation in clonal and sparse mass culture systems. As analyzed by cell biological (cell type frequencies), biochemical (collagen synthesis) and molecular markers (expression of protein PIVa) human skin and lung fibroblasts are induced to differentiate prematurely into terminal postmitotic cells. Thus, both electromagnetic and ionizing radiation induce terminal differentiation in cultured cells. These data add some new aspects for the interpretation of radiation effects on cells, e.g., in clinical therapy, as well as for the development of normal tissue responses during early and late effects after radiotherapy.