Biomedical subjects

K Hietaniemi

Publications and source records attributed to K Hietaniemi.

11 recordsLinked to original sources

PubMed2001

In vivo glucose-stimulated amylin secretion is increased in nondiabetic patients with pancreatic cancer.

The incidence of diabetes is increased in patients with pancreatic cancer, but the mechanisms underlying this association are not clear. Alterations in beta-cell function, such as formation of amyloid from excessive production of amylin and reduced expression of GLUT2, have been suggested to be possible mechanisms. We compared in vivo secretory responses of amylin and insulin (n = 37) and expression of GLUT2 in pancreata (n = 10) obtained at surgery between diabetic and nondiabetic patients with and without pancreatic tumors. Fourteen had pancreatic adenocarcinoma, 7 had diabetes (duration 6 +/- 3 years) and a pancreatic tumor, 8 had type 2 diabetes (duration 6 +/- 2 years), and 8 were normal subjects. First (0 to 10 minutes) and second (10 to 120 minutes) phase insulin and amylin secretion were characterized using the hyperglycemic clamp technique. Both amylin and insulin concentrations followed a biphasic pattern in nondiabetic subjects. In nondiabetic patients with pancreatic cancer, total, as well as nonglycosylated amylin concentrations, were increased compared with nondiabetic subjects without pancreatic cancer. Both first- and second-phase plasma amylin and serum immunoreactive insulin concentrations were low in all patients with diabetes, ie, both in type 2 diabetes and in those patients with diabetes and pancreatic tumors. At surgery, specimens were obtained for characterization of GLUT2 expression in beta cells, which was unaltered in nondiabetic (n = 7) and diabetic (n = 3) patients. Amyloid staining was similarly negative in diabetic and nondiabetic pancreata independent of pancreatic carcinoma. In conclusion, plasma amylin, but not insulin concentrations, are increased in nondiabetic patients with pancreatic cancer, but low in all patients with diabetes. These data support the potential of using an increase in the ratio of circulating amylin to insulin as a marker for pancreatic cancer in nondiabetic patients.

Adenocarcinoma↗

PubMed1998

Major fibrillar collagens and fibronectin in an experimental nonunion: an immunohistochemical study.

We studied in a rat pseudoarthrosis model the time sequence of expression and distribution of fibronectin and collagens I, II, III and V. Collagens and fibronectin were immunolocalized at the light microscopic level. The major difference from the normal healing pattern was the extension of collagen II and cartilage into the interfragmentary area and at the circumference of the periosteal callus, without any bridging chondral or bony elements in the fracture gap. The formation of a fibrous bond, consisting mostly of collagen III and fibronectin, was observed. This speaks in favor of the failure of the multipotentional mesenchymal stem cells to change the fracture-healing process towards fibroblast proliferation and the production of tissue unable to mineralize. The decisive zone for mineralization of the callus appeared to be the area of the hypertrophied chondrocytes near the periosteal ossification front.

Animals↗

PubMed1998

Retarded mineralization cascade in an experimental nonunion--a sequential polyfluorochrome labeling study in rats.

BACKGROUND AND AIMS: Although the early phases of the healing seem to occur normally, the persistent rotational instability between the fracture fragments combined to periosteal manipulation at the fracture site cause a failure in the restoration process of bone; i.e. the bridging event of the fracture ends does not occur and the tissue in the interfragmentary area is not mineralized. A nonunion with a soft tissue connection between the fragments is formed without restoration of the biomechanical characteristics of the bone. MATERIAL AND METHODS: A nonunion model of the rat femur was employed to study the mineralization process of developing pseudoarthrosis using the sequential polychrome labeling and conventional histological hard tissue staining with Masson-Goldner trichrome method. RESULTS AND CONCLUSIONS: The same results of this study are in accordance with previous studies using the same nonunion model and suggest that if sufficient mechanical stability between the fracture fragments has not been achieved within optimal time period, the chondral phase of the callus is extended and the mineralization process of the hypertrophied chondrocytes is retarded and finally extinguished and the fracture gap is filled with non-mineralizing connective tissue.

Animals↗

PubMed1997

Neck injury after repeated flexions due to parachuting.

A 37-yr-old, previously healthy officer developed a severe pain in the right shoulder and parethesia in the right I-III fingers during a high-altitude low-opening parachute jump. The pain started after a sudden neck flexion while he was checking the developing canopy, well before landing. Electroneuromyography revealed damage to the right C7 nerve root. Cervical radiography showed severe spondylosis and discus degeneration in the CV-VII region; magnetic resonance image demonstrated posterior disk protrusions in this area. Military aviators flying high-performance aircraft often have similar problems in the cervical spine; they have been attributed to effects of high + Gz forces in association with twisted head positions. Parachutists appear to face similar risks. Selection of the optimal head position during the parachute opening and use of light helmets should be emphasized.

Adult↗

PubMed1996

Connective tissue parameters in experimental nonunion.

A previously developed experimental model for producing nonunions in rats was used to study the biochemical changes of connective tissue parameters in impaired fracture repair. The model is based on rotational instability between the fracture fragments. A mid-diaphyseal femoral osteotomy was performed on 30 male rats and fixed with a loose-fitting intramedullary nail. The rats were killed 1, 2, 3, 7, 9, and 12 weeks postoperatively, and the development of nonunions was verified with radiographs. The calluses were dissected free and set for biochemical analysis. The contents of nitrogen, hydroxyproline, calcium, and phosphorous, as well as the RNA/DNA ratio, were determined. It appeared that in the impaired fracture repair there is an extended matrix production phase continuing until 7 weeks postoperatively. Simultaneously, the number of callus cells increased, indicating an extended expression of the mitotic signals for callus cells. The net synthesis of collagen matrix seemed to be sufficient, but the mineral binding capacity of the newly synthetised collagen was impaired. Later, the cessation of chondrogenic and osteogenic activity could be observed with the formation of nonmineralized fibrous tissue between the fracture fragments.

Animals↗

PubMed1995

An experimental model for non-union in rats.

Few studies of the biological changes which occur in impaired fracture repair and non-union have been carried out, and creating an appropriate model for advanced biochemical studies of non-union has proved to be a demanding task. This paper presents a standardized experimental model for producing non-union in rat femurs, for use in biochemical studies of non-union. A mid-diaphyseal fracture with a rotationally unstable fixation was performed in rats with a mean weight of over 330 g and mean age of over 10 weeks. Radiologically and histologically (Alcian blue and Safranin O stainings) the signs of undisturbed fracture healing were observed until 3 weeks after the fracture. Thereafter there was evidence that chondrocytic activity ceased, with no signs of formation of calcifying bridging callus. From the seventh week onwards, all elements necessary for a calcifying callus were lost; and the histological picture tended to be of scar tissue bond between the fracture ends.

Animals↗

PubMed1995

Extended expression of cartilage components in experimental pseudoarthrosis.

The healing of femoral fractures in an experimental rat pseudoarthrosis model was followed by studying the expression of cartilage specific genes coding for type II and X collagens and aggrecan, soft tissue and bone specific type I collagen, and decorin. Severe impairment of healing was observed with cartilage gene expression continuing until the seventh week and then declining rapidly. The abnormal healing pattern results in an inactive scar-like callus after the ninth week of healing even though house-keeping (e.g., GAPDH) genes are continuously expressed in the tissue. These results could be explained on the basis of continuous chondrogenic stimulus extending much beyond the normal range. If union is not achieved because of mechanical instability, signal of endochondral ossification persists until it becomes exhausted and callus at the fracture gap becomes an inactive fibrous scar. The disturbed matrix gene expression was confirmed by histology.

Aggrecans↗

PubMed1992

Displaced stress fracture of the femoral shaft: a report of three cases.

Three cases of displaced stress fracture of the femoral shaft are reported. All patients were young conscripts. Before displacement, the patients had suffered from knee and distal femoral pains for 2-6 weeks. All fractures were located at the border of the middle and distal third of the femoral shaft and had a short oblique form. Plating was performed in two and intramedullary nailing in one case. A fast bony union into a good position was achieved in all cases. Scintigraphy is indicated for an early diagnosis, which enables conservative treatment and prevention of the fracture displacement.

Adult↗

PubMed1990

Transcutaneous oxygen tension during prostacyclin infusion in distal limb ischaemia.

Transcutaneous oxygen tension measurement is an established method for monitoring immediate drug actions. The effects of prostacyclins in advanced limb ischaemia are controversial. To evaluate the immediate effects of epoprostenol infusion (10 ng/kg/min) on forefoot circulation, ten patients with distal ischaemia lesions were evaluated. During infusions systemic blood pressure was lowered, toe temperature elevated but transcutaneous oxygen tension was not changed. These results suggest a vasodilating action of the epoprostenol but contradict immediate positive effects on skin oxygenation.

Adult↗

PubMed1989

Association between dental health and acute myocardial infarction.

Known risk factors for coronary heart disease do not explain all of the clinical and epidemiological features of the disease. To examine the role of chronic bacterial infections as risk factors for the disease the association between poor dental health and acute myocardial infarction was investigated in two separate case-control studies of a total of 100 patients with acute myocardial infarction and 102 controls selected from the community at random. Dental health was graded by using two indexes, one of which was assessed blind. Based on these indexes dental health was significantly worse in patients with acute myocardial infarction than in controls. The association remained valid after adjustment for age, social class, smoking, serum lipid concentrations, and the presence of diabetes. Further prospective studies are required in different populations to confirm the association and to elucidate its nature.

Adult↗

PubMedDate not supplied

Leg lengthening by osteotomy and gradual distraction: an experimental study.

Osteotomy and gradual distraction of the distal radius was performed on 12 sheep. After 3-6 weeks of daily distraction by external fixation, lengthening of 0.5-1.8 cm was achieved. Three weeks after distraction was begun, striae of new bone, organized in the direction of the distraction, were noted radiologically. The bony consolidation developed from the osteotomized bone ends to the center of the distraction area. Medullary structures also contributed to bone formation in the distraction area. Collagen bundles, organized in the direction of distraction, formed a template for the developing bone. The medullary canal remodeled 16 weeks after the operation. Solid bone formed after the distraction procedure with no additional bone transplantation.

Animals↗