Chronic, definition

Toxicology. The acute oral and dermal toxicity of naphthalene is low with LD q values for rats from 1780—2500 mg/kg orally (41) and greater than 2000 mg/kg dermally. The inhalation of naphthalene vapors may cause headache, nausea, confusion, and profuse perspiration, and if exposure is severe, vomiting, optic neuritis, and hematuria may occur (28). Chronic exposure studies conducted by the NTP ia mice for two years showed that naphthalene caused irritation to the nasal passages, but no other overt toxicity was noted. Rabbits that received 1—2 g/d of naphthalene either orally or hypodermically developed changes ia the lens of the eye after a few days, foUowed by definite opacity of the lens after several days (41). Rare cases of such corneal epithelium damage ia humans have been reported (28). Naphthalene can be irritating to the skin, and hypersensitivity does occur. 

The definition above has replaced older ones that focused to varying degrees on chronic bronchitis and/ or emphysema. Chronic bronchitis and emphysema frequently represent different consequences of the same insult leading to changes in large aiiways, small airways and pulmonary parenchyma (Table 1). 

Because C02 is a volatile acid, it can rapidly be changed by the respiratory system. If a respiratory acid-base disturbance is present for minutes to hours it is considered an acute disorder while if it is present for days or longer it is considered a chronic disorder. By definition, the metabolic machinery that regulates HC03 results in slow changes in serum bicarbonate and all metabolic disorders are chronic. This means that there are six simple acid-base disorders as outlined in Table 25-1.2... 

Historically, osteomyelitis has been classified as acute or chronic based on duration of disease (Fig. 78-2).2,4 However, there are no established definitions for acute and chronic infections.2-4 Acute infection has been defined as first episode or recent onset of symptoms (less than 1 week).2,3 Chronic osteomyelitis is generally defined as relapse of the disease or symptoms persisting beyond 4 weeks.2,3 Others describe chronic osteomyelitis as the presence of necrotic bone.3 ... 

Microbial virulence is often the outcome of the complex interactions that take place as the pathogen establishes itself in the human host. The molecular determinants of pathogenicity include factors that cause damage to the host cell and those that help the microbe establish productive infection for survival [35]. The human host immune response counters the presence of these microbes with its acquired or innate immune response arsenal with outcomes that range from acute to chronic or latent infections. A clear definition of the host and microbial... 

The diagnosis of chronic bronchitis is based primarily on clinical assessment and history. By definition, any patient who reports coughing up sputum on most days for at least 3 consecutive months each year for 2 consecutive years suffers from chronic bronchitis. Table 43-1 presents a classification and treatment scheme for chronic bronchitis. 

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