Evaluation of a rapid culture-based screening test for detection of methicillin resistant Staphylococcus aureus

The performance of a culture based assay, BacLite Rapid MRSA for the rapid detection (5 hours) of methicillin resistant Staphylococcus aureus (MRSA) from specimens (n = 377) obtained from nares, throat, wounds and perineum was investigated. Compared to culture based reference methods (chromogenic MRSA ID (bioMerieux)), selective enrichment broth, PBP2' latex agglutination (Oxoid) and VITEK 2 identification (bioMerieux), an overall sensitivity of 71% with a 82% specificity and a negative predictive value (NPV) of 95% was provided. The Baclite test is rapid and easy to use and has the advantage of a culture-based detection method for MRSA.

Expression of matrix-metalloproteases in the fluid of chronic diabetic foot wounds treated with a protease absorbent dressing

It is well known, that wound healing in diabetes is impaired. Persistently high levels of matrix-metalloproteases (MMPs) contribute to wound persistence. The topical use of protease-inhibitors might beneficially affect wound healing.

RESEARCH DESIGN AND METHODS

19 patients with chronic diabetic foot lesions (Wagner/Armstrong 2A) were studied. 6 patients received "good standard wound care", 13 patients were treated with a protease-inhibitor-modulating-matrix (ORC/collagen matrix) that was changed daily. At day 1 and 5 biopsies were taken from the wounds; wound fluids were collected daily. Biopsies were analysed using quantitative real-time-PCR and all samples were analysed using ELISA and zymography for MMPs, TIMPs, IL 1-β and TNFα levels.

RESULTS

No differences in mRNA-expression of MMPs, TNFα and for MMP levels in wound tissue were detected between both groups or between the 2 sampling time points. MMP-2 active was significantly reduced in wound fluids of ORC/collagen treated lesions (p=0.043) after 5 days. MMP-2 pro was also reduced by about 25% when compared to increasing levels in the control group (+27%). We observed a significant reduction of the wound area in the ORC/collagen group (p=0.003).

CONCLUSIONS

Local treatment with a protease-inhibitor has a beneficial effect on wound healing. In contrast to unchanged mRNA-levels and protein levels of MMPs there was a clear reduction of MMP-2-levels in wound fluids. Our data support the potential role of ORC/collagen as a wound dressing. Modulation of MMPs appears to be beneficial in the treatment of chronic diabetic wounds.

[Unusual cause of abdominal lymphomas]

A 72 year old HIV-negative patient without relevant immunosuppression presented with abdominal lymphomas and inflammatory signs in the colon. Mycobacterium intracellulare was grown from colonic biopsies and stool. There was no sign of malignancy or chronic inflammatory bowel disease. We diagnosed an atypical, gastrointestinal mycobacteriosis und treated the patient accordingly. This led to a good response.

Endogenous ACTH, not only alpha-melanocyte-stimulating hormone, reduces food intake mediated by hypothalamic mechanisms

ACTH and alpha-melanocyte-stimulating hormone (alpha-MSH) are both consecutively processed from proopiomelanocortin (POMC), which is synthesized in hypothalamic arcuate neurons innervating the paraventricular nuclei (PVN). POMC secretion/synthesis is regulated by energy availability. ACTH and alpha-MSH bind with equal affinity to melanocortin-4 receptors and elicit similar effects on signal transduction in-vitro. Endogenous alpha-MSH thus far is believed to be the major physiological agonist and to act in an anorexigenic manner. Until now, it was fully unknown whether endogenous ACTH is also involved in the regulation of appetite and food intake. In this study in rats, we now show that icv ACTH as well as alpha-MSH possess anorexigenic effects in the PVN or areas in close proximity in vivo and that the effect of ACTH is direct and not mediated via alpha-MSH. We investigated the roles of endogenous ACTH and alpha-MSH by PVN application of the respective antibodies under different physiological conditions. In satiated rats with high levels of ACTH and alpha-MSH in the PVN, antibody administration increased food intake and body weight gain; hungry animals were unaffected. Finally, repeated injections of ACTH antibodies into PVN resulted in persistently increased food intake during the light period. These data now provide robust evidence that endogenous ACTH without further processing acts in the PVN or areas in close proximity to reduce food intake under conditions of feeding-induced satiety.

Mean cell volume of neutrophils and monocytes compared with C-reactive protein, interleukin-6 and white blood cell count for prediction of sepsis and nonsystemic bacterial infections

Clinicians are in need of better diagnostic markers for rapid diagnosis of severe infections. Therefore, we studied the diagnostic significance of mean cell volume of neutrophils (MNV) and monocytes (MMV) compared with Interleukin-6 (IL-6), C-reactive protein (CRP) and white blood cell count for predicting systemic clinical infection (sepsis). MNV and MMV were obtained by volume conductivity scatter (VCS) technique of the Coulter LH 750 hematology analyzer during automated differential counts, and blood samples from patients with sepsis (n = 37), nonsystemic bacterial infections (n = 39) and controls (n = 48) were studied. We observed a significant increase in MNV and MMV in the sepsis group compared with limited infections and controls. However, at a designated cut-off point of 250 pg/ml, IL-6 seemed to be the best predictor for sepsis with a sensitivity of 93% and a specificity of 76%. Compared with CRP (cut-off point 60 mg/dl), MNV at a cut-off of 150 had a comparable sensitivity and specificity and was the most predictive VCS parameter. Taken together, MNV and MMV seemed to be potential parameters to discriminate between sepsis and nonsystemic infections.

Association between diabetic-autonomic-C-fibre-neuropathy and medial wall calcification and the significance in the outcome of trophic foot lesions

The role of peripheral autonomic nerve failure in the development of medial arterial calcification is discussed controversially in the literature. In addition, the influence of medial wall calcification in the development of trophic foot lesions is still not fully understood. We have compared 28 diabetic patients with cardiac autonomic failure and/or decreased acetylcholine-induced sweat response with 22 diabetic patients without evidence of diabetic neuropathy and 27 healthy control subjects. A strong association was found between medial wall calcification and diminished heart rate variation (p.001) or diminished peripheral sweat response (p < 0.001). Only one subject in the control group exhibited a calcification of the tunica media in the lower limb. Medial calcinosis was accompanied by a significant rise of systolic ankle blood pressure (p < 0.05). In addition, there was a strong relationship between medial wall calcification and trophic foot lesions (p < 0.0001). Our results demonstrate a strong association between sympathetic C-fibre neuropathy and the development of medial wall calcification, as well as between calcification of the tunica media and trophic foot ulceration. Further investigation is necessary to determine whether there is a causal connection between medial arterial sclerosis and diabetic foot ulceration, or whether both are independent consequences of diabetic neuropathy.

[Differential value of the diagnostic options to determine the level of amputation]

The level of amputation after utilizing all possible options of revascularization is considered one of the substantial criteria for sufficient reconvalescence, recovery of mobility, reduction of perioperative mortality and, finally, social reintegration. In case of vascular genesis, the possibilities to reestablish or improve arterial perfusion need to be proven. According to the data from the literature on the various technical methods, only the ptO2 measurement has become widely accepted to determine efficiently the level of amputation. In addition, study results have given evidence for the distal shifting to the genual and infragenual level of amputation. Furthermore, a good prognostic value has been achieved with measures of radionuclide imaging. An alternative but simple procedure including influencing factors and standards of measurement is the determination of the systolic occlusion pressure. Further technical advances can be achieved by a combination of methods but this requires the systematic verification prior to their use. However, their technical potential and options appear to be not fully utilized yet.

[Specific characteristics of amputations of the lower leg: the physicians view]

Amputations are relevant problems not only for the surgeon. Physicians and dialectologists are also involved into the wound treatment, the coordination of the attending problems which leads to impaired wound healing (e.g. hyperglycaemia, infection, arterial occlusive disease). Internists should be part of the interdisciplinary setting and also of the decision for the necessary amputation. A well coordinated and interdisciplinary procedure allows to control appearing wound healing disturbances and to receive a functionally optimal result by employing minimal surgical interventions.

Interleukin-6 concentrations in wound fluids rather than serological markers are useful in assessing bacterial triggers of ulcer inflammation

Bacterial pathogenicity, microbial load and diversity are decisive for outcome and therapy of non healing ulcers. However, until now, no routine laboratory parameter is available to assess the inflammatory level caused by chronic wound infections. We thus investigated the usefulness of levels of interleukin (IL)-6 and tumour necrosis factor alpha (TNFalpha) in wound fluids for assessing ulcer inflammation in the presence or absence of microbial triggers. In addition, the predictive values of local cytokine analyses were compared with those of C-reactive protein (CRP) and lipopolysaccharide-binding protein (LBP) because serological markers are normally used to underline the suspicion of wound infections. The present data from chronic arterial and venous ulcers (n = 45) clearly show that mixed bacterial infections increased IL-6 and TNFalpha concentrations in wound fluids when compared with ulcers with a monomicrobial infection (P < 0.01 and P < 0.05, respectively). IL-6 was also significantly elevated when a high bacterial load [versus <10(5) colony-forming units (cfu)/ml: P = 0.04] or an infection with Pseudomonas was observed (versus isolation of non Pseudomonas strains: P = 0.05). Although distinct proinflammatory triggers may interfere with regard to cytokine levels, sensitivity and specificity were significant in predicting bacterial risk factors, particularly for IL-6 at a designated cut-off of 125 pg/ml (sensitivity and specificity for predicting a mixed infection: 70% and 64%, for predicting a bacterial load of >10(5) cfu/ml: 62% and 57% and for predicting an infection with Pseudomonas: 90% and 57%). In contrast to local cytokine levels, the serological markers CRP and LBP were not associated with the presence of any of the investigated bacterial triggers. Focusing on the aim of the study, IL-6 analysed in wound washouts seems to be a useful diagnostic marker for a sensitive and specific assessment of ulcers inflammation with regard to bacterial triggers.

The influence of polymorbidity, revascularization, and wound therapy on the healing of arterial ulceration

OBJECTIVE

An ulcer categorized as Fontaine's stage IV represents a chronic wound, risk factor of arteriosclerosis, and co-morbidities which disturb wound healing. Our objective was to analyze wound healing and to assess potential factors affecting the healing process.

METHODS

199 patients were included in this 5-year study. The significance levels were determined by chi-squared and log-rank tests. The calculation of patency rate followed the Kaplan-Meier method.

RESULTS

Mean age and co-morbidities did not differ from those in current epidemiological studies. Of the patients with ulcer latency of more than 13 weeks (up to one year), 40% required vascular surgery. Vascular surgery was not possible for 53 patients and they were treated conservatively. The amputation rate in the conservatively treated group was 37%, whereas in the revascularizated group it was only 16%. Ulcers in patients with revascularization healed in 92% of cases after 24 weeks. In contrast, we found a healing rate of only 40% in the conservatively treated group (p<0.001). Revascularization appeared more often in diabetic patients (n=110; p<0.01) and the wound size and number of infections were elevated (p=0.03). Among those treated conservatively, wound healing was decelerated (p=0.01/0.02; chi(2) test).

CONCLUSIONS

The success of revascularization, presence of diabetes mellitus, and wound treatment proved to be prognostic factors for wound healing in arterial ulcers.

Expression of matrix metalloproteinases, cytokines, and connexins in diabetic and nondiabetic human keratinocytes before and after transplantation into an ex vivo wound-healing model

OBJECTIVE

Wound healing is known to require a well-organized balance of numerous factors, e.g., cytokines, matrix metalloproteinases (MMPs), and their inhibitors, as well as direct cell-cell communication (connexins). Disruption of this balance may lead to the formation of chronic wounds such as diabetic foot ulcers. The transplantation of autologous keratinocytes is a promising therapy for diabetic foot ulcers; however, little is known about their characteristics on a molecular level. Therefore, we intended to characterize transplanted keratinocytes from diabetic and nondiabetic origin before and after transplantation.

RESEARCH DESIGN AND METHODS

We isolated human keratinocytes from diabetic and nondiabetic origins and transplanted them into an ex vivo wound healing model. To characterize the keratinocytes, we investigated mRNA expression of MMP-1, MMP-2, and MMP-9; tissue inhibitor of MMP (TIMP)-1 and TIMP-2; interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha; Cx26 (connexin 26) and Cx43; and, for connexins, immunolocalization.

RESULTS

We found no significantly increased expression of the molecules investigated in cultured keratinocytes from diabetic compared with nondiabetic origin, even though there were significant differences for MMP-2, IL-1beta, and TNF-alpha in skin biopsies. Expression of IL-1beta was significantly lower in keratinocytes from diabetic origin. In the course of wound healing, differences in the dynamics of expression of MMP-1, IL-1beta, and Cx43 were observed.

CONCLUSIONS

Our results suggest that keratinocytes from diabetic origin are as capable for transplantation into chronic wounds as keratinocytes from healthy origin at the starting point of therapy. However, differences in expression dynamics later on might reflect the systemic influence of diabetes resulting in a memory of the transplanted keratinocytes.

Expression of matrix metalloproteinases and growth factors in diabetic foot wounds treated with a protease absorbent dressing

Wound healing in diabetes is impaired, and nonhealing ulceration represent clinically relevant complications. Persistently high levels of matrix metalloproteases (MMPs) contribute to wound chronicity. Thus, the topical use of protease inhibitors might influence wound healing and promote transition from a chronic to an acute wound.

METHODS

In this study, 33 patients with chronic diabetic foot lesions (stage 2a of the University of Texas Wound Classification system) were included. Fifteen patients received redundant "good standard wound care." In addition, 18 patients were treated with a protease inhibitory modulating matrix (the OCR/collagen Promogran matrix, Ethicon) with dressings changed on a daily basis. Prior to treatment and at 4 and 8 days after treatment, two 3-mm punch biopsies were taken from the center of the wounds and analyzed using ELISA techniques for MMPs, tissue inhibitor of MMP-2 (TIMP-2), and interleukin-1beta (IL-1beta) levels. In addition, mRNA levels of MMPs as well as IL-1beta and TNF-alpha were detected using quantitative real-time polymerase chain reaction (TaqMan, Applied Biosystems, Weiterstadt, Germany).

RESULTS

No differences were detected between both groups and at the three time points for the mRNA levels of MMPs as well as of IL-1beta and TNF-alpha. In addition, MMP levels in wound tissue (analyzed by ELISA) were also not significantly different between both groups. However, IL-1beta was increased on day 8 in the treatment group (P=.01) only. Interestingly, we found a significant reduction of the MMP-9/TIMP-2 ratio in the group being treated with the ORC/collagen. These wounds exhibited a more rapid healing rate when treated with the ORC/collagen matrix.

CONCLUSIONS

The local treatment with a protease inhibitor has a beneficial effect on wound healing. In contrast to the data on wound fluid, our study demonstrated for the first time the unaltered mRNA levels of MMPs during treatment with a protease inhibitory modulating matrix. At the cellular level, MMPs were also not statistically different. However, the more relevant ratio of MMP-9/TIMP-2 was decreased in the treatment group. An equally important finding was that we did not detect a compensatory increase in the MMP-RNA expression even though wound size was clearly reduced.

[Microalbuminuria in diabetes: setting the points for treatment]

Both type 1 and type 2 diabetes mellitus have a cumulative risk of 25-40% for the development of microalbuminuria 25 years into the disease. In type 2 diabetes micro- and macroangiopathic complications, and frequently hypertension, may also develop. This means that the risk of a type 2 diabetic with microalbuminuria of developing cardiovascular disease is three times greater than that of a diabetic with no renal involvement. Annual screening for microalbuminuria should therefore be obligatory. An increasing albumin excretion rate (AER) is considered an indication for an elevated cardiovascular risk. Studies have shown that the rate of cardiovascular events in diabetics with microalbuminuria and hypertension can be reduced only by the combined treatment of hypertension, hyperglycemia, hyperlipidemia and microalbuminuria.

Differential effects of PDGF-BB on matrix metalloproteases and cytokine release in fibroblasts of Type 2 diabetic patients and normal controls in vitro

AIMS/HYPOTHESIS

The complex process of wound healing is regulated by various growth factors. The systemic character of diabetes mellitus favors the chronification of diabetic wounds. In this study, the in vitro effects of platelet-derived growth factor (PDGF)-BB on the expression of cytokines and matrix metalloproteases (MMPs) in fibroblasts of Type 2 diabetic patients and healthy controls were investigated.

METHODS

We studied six Type 2 diabetic patients (mean Hba1(c)=7.5%) and six healthy controls. For proliferation studies, cultivated fibroblasts, prepared from biopsies taken from the thigh, were stimulated with different concentrations of PDGF. After 48 h, the expression of MMPs and cytokines was measured. We analysed the mRNA expression by RT-PCR (TaqMan), tissue protein levels by zymography, and cell supernatant levels by ELISA.

RESULTS

Levels of MMP-mRNA were elevated in diabetic fibroblasts compared with healthy controls. At baseline, MMP-2 protein levels were significantly increased in the fibroblast of diabetic patients (P=.019). For MMP-9, a trend towards higher levels (P=.3) was found. After incubation with PDGF, a significant reduction of MMP-9 (P=.01) and MMP-13 (P=.04) was found. Analysis of cytokine release in cell culture supernatant showed elevated levels of interleukin (IL)-8 at baseline conditions. MMP-1 and MMP-2 levels in the supernatant were concentration-dependently reduced.

CONCLUSIONS

This study, for the first time, demonstrates elevated MMPs in cultivated fibroblasts (derived from intact skin and not from an open wound) of diabetic patients compared with healthy controls under in vitro conditions. Therefore, our data support the hypothesis of alterations of wound healing in diabetic patients on the cellular level, reflecting the systemic character of the disease.

Hypoglykämie trotz Hyperglykämie

Hypoglycemia represents the most frequent endocrinologic emergency situation in prehospital patient care. As the patients are usually unconscious on arrival of emergency medical personnel, often the only way to establish a diagnosis is by determination of the blood glucose concentration. However, even normoglycemic or hyperglycemic levels cannot definitively exclude the diagnosis of a previous hypoglycemia as the cause of the acute cerebral deficiency. Therefore, and especially in the case of insulin-dependent diabetes mellitus, a differential diagnosis should be considered. We report a case of emergency treatment of a hypoglycemic episode in a female patient with prolonged neuroglycopenia together with cerebrovascular dementia and Alzheimer's disease.

Expression of cell surface antigens in diabetic patients and healthy controls after injury

AIMS

Due to the systemic character of Type 2 diabetes, cellular disturbances paralleled by an altered expression of various growth factors constitute the basis for impaired wound healing. Cell-surface antigens are altered in chronic wounds and may also have an effect on the persistance of diabetic foot lesions.

METHODS

We investigated blood samples of diabetic patients with diabetic foot ulcers (n=21) in comparison with those from healthy control patients subsequent to an injury (n=9). A blood sample (EDTA) was taken from each participant (in the trauma control group on the third day after injury) and examined by flow cytometry [fluorescence-activated cell sorter (FACS)]. Typical cell surface antigens involved in wound healing were studied [cluster of differentiation (CD)2, CD3, CD4, CD25 and human leukocyte antigen (HLA)-diabetic retinopathy (DR)].

RESULTS

known to adversely affect wound healing were elevated in diabetic patients (CD2 p<0.001; CD3 p=0.016, CD4 p=0.22, CD25 p<0.001). HLA-DR expression was also decreased in diabetic foot patients (p=0.023).

CONCLUSIONS

Cell-surface antigens appear to be altered in diabetic patients when compared to healthy controls. Thus, due to the systemic character of Type 2 diabetes, cellular disturbances may well constitute the basis for impaired wound healing in diabetes.

Antibiotic therapy for diabetic foot infections: comparison of cephalosporines with chinolones

Diabetic foot complications are the most common cause of non-traumatic lower extremity amputations and uncontrolled infections represent a major risk factor. This open prospective, multicenter trial compared the efficacy of two antibiotic regimens for treatment of foot infections Wagner stage II or III in diabetic adults. Three hundred diabetic patients with severe, limb-threatening foot infection were consecutively enrolled in a prospective, observational, matched pairs controlled study to test two different antibiotic regimes (ceftriaxone vs chinolones) in addition to standard treatment of foot infection. After matching, 90 patients--each receiving ceftriaxone or chinolones--were analyzed. Our study demonstrated that treatment with a third generation cephalosporine is as effective as a treatment with chinolones. Response (reaching Wagner I or 0) was achieved in 58.0% in the ceftriaxone group and in 51.1% in the chinolone group (NS.). Fourteen days after initiation of treatment, the number of patients with microbiological isolates decreased in both groups (52 to 5 in the ceftriaxone group and 60 to 12 in the chinolone group). At hospital discharge, 66.0% of ceftriaxone and 64.4 of chinolone-treated diabetic ulcers were cured or improved. In summary, both substances proved to be effective in the primary antibiotic treatment of the diabetic foot; an early broad spectrum antibiotic treatment, that covers both gram-positive and gram negative bacteria as well as anerobes is undisputedly an imperative therapeutic intervention for the treatment of diabetic foot infection.

[Hypoglycemia, classification, therapy and preventable errors]

Hypoglycemia is a multifactorial problem that is caused by the interaction of numerous variables such as a individual pathophysiological response, treatment aspects and self control. In particular, the increasing use of intensified insulin therapy and thus the goal of normoglycemia has made hypoglycaemia to become a major hazard among the acute complications of diabetes mellitus. Early diagnosis and treatment is thus mandatory to reduce the increased morbidity and mortality of hypoglycaemia. Among the acute therapy of hypoglycaemia treatment includes a modification of diabetes therapy, patient education and a special training of hypoglycaemia awareness.

Autologous human keratinocytes cultured on membranes composed of benzyl ester of hyaluronic acid for grafting in nonhealing diabetic foot lesions: a pilot study

Diabetic foot complications are the most common cause of nontraumatic lower extremity amputations in the industrialised world. Unsatisfactory healing requires advanced therapeutic strategies, such as the use of skin grafts, which may represent a helpful option for wound coverage. Alternatively, a method using autologous keratinocytes grown to thin sheet grafts is available. The purpose of this pilot study was to investigate the application of autologous human keratinocytes cultured on membranes composed of benzyl ester of hyaluronic acid (Laserskin autograft) to diabetic foot ulcers. We studied 14 patients with type 2 diabetes mellitus and a nonhealing diabetic foot lesion, defined as existing longer than 6 months or with no wound healing apparent for 12 weeks. Between 7 and 64 days after the transplantation (depending on the size of the ulceration), 11/14 of the lesions were completely healed. The transplantation of autologous keratinocytes may allow faster closure of diabetic foot lesions and subsequently reduce length of hospitalization. This method can easily be planned with regard to logistics and time, and furthermore, this therapy option can be carried out by the diabetologist.

[Microbiological aspects and antibiotic therapy of diabetic foot infections]

IMMUNOLOGICAL AND MICROBIOLOGICAL ASPECTS OF DIABETIC FOOT INFECTIONS: Diabetic patients are at increased risk of severe skin and bone infections. Immunological disturbances are reasonable and due to altered specific and unspecific cellular immune responses. Analysis of epidemiology and microbial pathogenicity shows that staphylococci seem to be predestined to induce such infections. Staphylococcus aureus and coagulase-negative staphylococci are able to adhere to the wound ground by a sequela of mechanisms. Initial bacterial adherence is due to hydrophobicity, ion exchanges, and specific binding of bacterial adhesion molecules to cellular receptors. Moreover, staphylococci secrete polysaccharides which form a biofilm together with multilayer cell clusters. The highly structured communities within a biofilm are resistant to distinct immunoeffectors and have a decreased susceptibility to antibiotics in vivo.

ASPECTS OF ANTIBIOTIC THERAPY

Assessing the severity of an infection is essential to selecting an antibiotic regimen, the mode of drug administration, and the duration of therapy. Regimens for severe and chronic infections are broader spectrum and often intravenously to obtain high drug concentrations immediately. Infections of the bone often require an antibiotic therapy for > 4 weeks, while a 1- to 2-week therapy for mild to moderate infections has been found to be effective.

CONCLUSIONS

Because of the tremendous progress in diagnostics and therapy of diabetic foot infections, infectious complications can be successfully treated by appropriate wound care, metabolic control, and early surgical and antibiotic intervention. Bacterial biofilms involved into chronic infections are new aspects currently not visualized by clinical therapy. Besides the classic antimicrobial therapy, new concepts of an enzymatic therapy or the inhibition of bacterial "communication" (quorum sensing) are in progress and the hope for the future.

[Molecular fundamentals of wound healing in diabetic foot syndrome]

BACKGROUND

The diabetic foot syndrome represents a considerable problem of health care. Due to the systemic character of diabetes mellitus, disturbances on the molecular level of wound healing are assumed.

PATHOGENESIS

Growth factors and proteases affect the process of normal wound healing, and changes of their activity are relevant to the pathogenesis of the chronic wound. First studies describe the transition of a diabetic foot lesion to a nonhealing chronic wound on the molecular and cellular level.

CURRENT RESEARCH

This review reports on the current status of research and new implications for the treatment of diabetic foot syndrome.

Pupil signs of sympathetic autonomic neuropathy in patients with type 1 diabetes

OBJECTIVE

Pupillary autonomic neuropathy is considered an early sign of the development of systemic autonomic neuropathy. Sympathetic denervation is related to the duration of diabetes and the development of systemic autonomic dysfunction. We investigated pupil responsiveness to directly and indirectly acting sympathomimetics in type 1 diabetic patients with and without long-term complications, defined as cardiac autonomic neuropathy (CAN), peripheral sensomotor neuropathy, retinopathy, and nephropathy, and in healthy subjects.

RESEARCH DESIGN AND METHODS

A total of 47 randomly chosen type 1 diabetic patients and 20 healthy subjects were selected for this study. Patients were divided into groups determined by whether they had long-term diabetic complications. Pharmacological tests were performed with cocaine 4%, epinephrine 1%, and pholedrine 5% eye drops. Horizontal pupil diameter (HPD) was measured at the beginning of the pharmacological tests and at defined time points after instillation of the eye drops.

RESULTS

Statistical analysis showed a significantly smaller HPD in the patients before instillating eye drops (P = 0.011). In particular, the HPD was significantly smaller in the patient group without CAN when compared with healthy subjects (P = 0.004). Maximal cocaine reaction was diminished in the complication group (P < 0.001). Epinephrine test, visual acuity, ocular pressure, and HbA(1c) did not differ in patients with or without long-term complications. The noncomplication group showed no significant differences in pupillary responses as compared with healthy subjects. The complication group showed a smaller HPD (P = 0.022), reduced pupillary responses in the cocaine (P = 0.037) and pholedrine tests (P < 0.001), and anisocor pupil sizes after instillation of the eye drops (P = 0.034).

CONCLUSIONS

Our results clearly show that sympathetic denervation does exist in the pupil of diabetic patients and that it can be rapidly assessed using the cocaine test. These data and the results of the epinephrine test suggest a mixed pre- and postganglionic dysfunction of the sympathetic plexus. The significant smaller HPD in patients without CAN compared with that of healthy subjects could be a sign for early involvement of the pupil function before cardiac manifestation of systemic autonomic diabetic neuropathy.

Expression of matrix-metalloproteinases and their inhibitors in the wounds of diabetic and non-diabetic patients

AIMS/HYPOTHESIS

The molecular factors that cause an acute wound in diabetic patients to become chronic have not yet been established. Wound healing is known to require a balance between the accumulation of collagenous and non-collagenous extracellular matrix components and their remodelling by matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs). Our aim was to assess if the concentrations of MMPs and TIMPs were different between acute and chronic wounds in diabetic patients by analysing biopsy samples.

METHODS

A 5 mm punch biopsy was taken from 20 diabetic foot ulcers of patients before initiating treatment and from traumatic wounds of 12 non-diabetic patients 2 days after injury. The concentrations of MMP-1, MMP-2(pro), MMP-2(active), MMP-8, MMP-9 and TIMP-2 were measured in detergent extracts of the biopsy homogenates using ELISAs and gelatin-zymography.

RESULTS

The concentration of MMP-1 was increased 65-fold in biopsies of diabetic foot ulcers compared with the concentrations measured in biopsies of traumatic wounds. Similarly, MMP-2(pro) were increased threefold, sixfold for MMP-2(active), twofold for MMP-8 and 14-fold for MMP-9 compared to average concentrations in biopsies of traumatic wounds. Furthermore, the expression of TIMP-2 was reduced twofold in diabetic wounds compared with lesions of non-diabetic patients.

CONCLUSION/INTERPRETATION

The combination of increased concentrations of MMPs with decreased concentrations of TIMP-2 in chronic diabetic foot ulcers compared with healing wounds in normal patients suggests that the increased proteolytic environment contributes to the failure of diabetic wounds to heal. New treatment strategies for healing chronic diabetic foot ulcers could be directed towards reducing concentrations of MMPs and increasing levels of TIMPs.

Association of increased plantar pressures with peripheral sensorimotor and peripheral autonomic neuropathy in Type 2 diabetic patients

AIM

Diabetic polyneuropathy plays a highly significant role in the pathogenesis of the diabetic foot syndrome. It was the objective of this study to investigate the association of different forms of neuropathy (cardiac autonomic, sensorimotor and peripheral autonomic) with elevated plantar pressures in diabetic patients.

METHODS

A total of 103 Type 2 diabetic patients was investigated. High plantar pressure was diagnosed when the total peak pressure was greater than 500 N/m2. Thirty-three participants were identified as patients with high-risk pressure and 70 patients had a mean peak pressure lower than 500 N/m2. All patients underwent a complete medical examination including determination of neuropathy, vascular status and foot pressures.

RESULTS

Peripheral sensomotoric (p<0.012) and peripheral autonomic neuropathy (p<0.05) were significantly found more often in patients with high plantar pressures. There was no apparent association between autonomic cardial neuropathy and enhanced foot pressure (p=0.175).

CONCLUSIONS

Our data clearly point to a correlation of diabetic neuropathy and higher plantar pressures. Interestingly, while there was a strong association between peripheral measures of neuropathy, no higher incidence of cardiac neuropathy in patients with increased foot pressure profiles was found. We strongly recommend that patients with clinical signs and indices of peripheral neuropathy be monitored by pedobarography for early detection and prophylactic shoe care for preventing the development of a diabetic foot ulcer.

[Strategies for control of diabetic foot syndrome. Amputation rate can be reduced!]

In two-thirds of the cases, wound healing can be achieved by good wound care, namely structured and stage-related management. Some 30% of the cases require extended and innovative therapeutic measures. In these complicated, poorly healing wounds, the supplementary use of special wound dressings or wound medication in the granulation phase can be considered. The application of such substances promoting wound healing (growth factors, cytokinin modulators, e.g. hyaluronic acid or protease inhibitors) may help to activate chronic lesions and thus initiate, and in particular abbreviate, healing. This aspect of reduced healing duration is of particular importance in the diabetic lesion, since it prevents or reduces secondary infection, the most common cause of major amputation.

Effects of preventative footwear on foot pressure as determined by pedobarography in diabetic patients: a prospective study

AIMS

This study analysed the effects of specially manufactured insoles on foot pressures in diabetic patients during a 1-year prospective observation period.

METHODS

We studied 81 type 2 diabetic patients without foot lesions. Using pedobarography three different regions of interest were examined: maximum peak pressure (MPP) of the total foot area, heel region and head of metatarsal bone I-III. Eighteen patients with high risk pressure (MPP of total foot 474 +/- 183 kPa; heel region 278 +/- 147 kPa, metatarsal 389 +/- 222 kPa) received optimal insole support. Sixty-three patients as a control group (MMP of total foot 367.7 +/- 157 kPa; heel 263.1 +/- 127 kPa, metatarsal 339.9 +/- 171 kPa) received conventional footwear.

RESULTS

After insole support a 30% pressure reduction of total foot MMP (474 +/- 183 kPa vs. 290 +/- 106 kPa) was achieved in the treatment group. After 6 months (324 +/- 127 kPa) and 1 year (380 +/- 190 kPa) a pressure reduction was found. Between the 6- and 12-month controls plantar pressures again increased. In the control group a significant increase of all peak pressures occurred.

CONCLUSIONS

Early insole support is successful in reducing plantar pressure. A repeated adjustment should be performed every 6 months to prevent foot pressure increases. The comparison of foot pressure development between the two groups showed constant levels in the treatment group. In the control group a marked increase of the pressure values was found. Identification and subsequent support of patients with high ulceration risk may help to reduce the high amputation rate.

Relation between homocysteinaemia and diabetic neuropathy in patients with Type 2 diabetes mellitus

AIMS

Limited data are available on determinants of diabetic neuropathy as its pathogenesis is multifactorial. Since homocysteine exhibits toxic effects on vascular endothelial cells, the association between homocysteine and the prevalence of neuropathy in Type 2 diabetes mellitus was investigated.

METHODS

A total of 65 Type 2 diabetic patients were consecutively enrolled into the study. Neuropathy was diagnosed according to clinical symptoms, clinical examination, electrophysiological sensory testing and autonomic function testing. With regard to homocysteine-related parameters, plasma homocysteine, folate, vitamin B12, vitamin B6 and renal function (creatinine, ceratinine clearance, cystatin C) were measured, and the C677T polymorphism of the methylenetetrahydrofolate reductase gene was determined.

RESULTS

Forty-three of the Type 2 diabetic patients were classified as suffering from neuropathy. Both patient groups were comparable with regard to demographic data, blood pressure, glucose metabolism, renal function and homocysteine-related vitamins. In contrast, homocysteine levels (P = 0.04) and the frequency of hyperhomocysteinemia (>or= 15 micromol/l) (P = 0.01) were significantly increased in neuropathic patients. In a logistic regression model with neuropathy as dependent variable, homocysteine (adjusted for creatinine, homocysteine-related vitamins, HbA1c and duration of diabetes) was the only significant variable associated with the prevalence of neuropathy (odds ratio for homocysteine per 5 micromol/l increase: 2.60 (95% confidence interval 1.07-6.33)).

CONCLUSION

The data indicate that homocysteine is independently associated with the prevalence of diabetic neuropathy in a collective of Type 2 diabetic patients. A larger, prospective study would be desirable to clarify the role of homocysteine in the pathogenesis of diabetic neuropathy.

Impairment and recovery of elementary cognitive function induced by hypoglycemia in type-1 diabetic patients and healthy controls

Although neuroendocrine changes after induction of hypoglycemia, in patients with diabetes and healthy persons, are thoroughly investigated, cognitive adaptation processes are still insufficiently understood. Changes in cognitive functions are mainly investigated by psychometric tests, which represent a summation of different cognitive processes. We aimed at dissecting cognitive adaptation into single components, i.e. stimulus selection, response choice, and reaction speed during a hyperinsulinemic hypoglycemic clamp in patients with type-1 diabetes and matched healthy controls. Using novel neurophysiological analyses, the event-related potentials of early stimulus selection (selection negativity) and response selection (lateralized readiness potential) were studied, in addition to reaction time (RT). A total of 12 diabetic patients and 12 normal volunteers were studied while receiving a hyperinsulinemic hypoglycemic clamp. RTs and the event-related potentials related to stimulus selection and response selection were significantly delayed during hypoglycemia in both groups, whereas early evoked potentials (P100) were unaltered. This suggests that hypoglycemia delays stimulus selection, with the consequence that also central and motor processing are delayed. In addition, patients with diabetes showed an earlier negative shift over the frontal cortex, which, when compared with the controls, reveals better adaptation to hypoglycemia in frontal cortical brain regions. After restoration of euglycemia stimulus selection, response selection and RT returned to baseline level in the type-1 group. In the control group, however, response selection and RTs were still delayed. This suggests that type-1 patients, possibly because of the past occurrence of hypoglycemic events, might be able to better cope with the hypoglycemic state than healthy volunteers who lack such a history. In summary, our data demonstrate, for the first time, that cognitive adaptation processes to an experimental hypoglycemic episode can clearly be dissected into their single components.